Recurring Riff

A Leitmotif that doesn't apply to a particular character; instead, it applies to a particular work or series. Sometimes a character's Leitmotif is even reused in an installment of a series where that character is not part of the story. Very popular in Video Games, but by no means exclusive to it. If used across a series, it can have nostalgic connotations. Obviously, Crossover games like Super Smash Bros. use the themes of the games represented to form the majority of the soundtrack.

No relation to the Sluggy Freelance character Riff. See Recurring Element for non-music examples, and Theme Tune Cameo for the series theme appearing in-universe.

Action Adventure

 * The Legend of Zelda. That fairie fountain/choose a file music just does not die.
 * The original overworld tune may be seeing less use these days, but snippets of it still crop up, pastiche-like, in the overworld music of the newer games.
 * The series also has two commonly-reused fanfares. The "Quest Item Obtained" fanfare and the "Puzzle Solve" fanfare are repeated frequently in the series, and the former has undergone MemeticMutation amongst gamers.
 * Some of the recurring tunes from previous games in Twilight Princess: Dinosaur Boss Battle, especially during the Stallord battle, the first riff of the original Kakariko Village music interpolated with a slow variation of the Dark World theme from A Link to The Past, Zora's Domain (almost identical to its Ocarina of Time incarnation), the opening riff of the title music from the original The Legend of Zelda, used in the intro sequence, Hyrule Castle, and Saria's Song, which is used as the Sacred Woods theme. Sadly, the original overworld theme is almost completely absent. The tune pops up on a more triumphant note about halfway though the ending credits and a few bars appear in the overworld music, but that's more-or-less it.
 * Not to mention the Song of Time used in the.
 * Particularly notable use of the theme in Wind Waker: You hear bars of the Zelda overworld theme during scenes which Link's heroic legacy and destiny are discussed, but never anywhere else.
 * Fridge Brilliance in that during Wind Waker, Hyrule no longer actually exists and is only discussed of in oral legend.
 * In addition, almost every game that has a dungeon taking place inside Hyrule Castle will have a variant on the Hyrule Castle theme from Link to the Past.
 * In Majora's Mask, the musics for each of the "provinces" (Woodfall, Snowhead, Great Bay, Ikana/Stone Tower) all share a common riff/melody with different instrumentations, which in turn, is based on Majora's theme.
 * The Title theme from A Link to the Past was used in The Wind Waker when  and also makes a small cameo in the scene where the Great Deku Tree tells the story of the Triforce, as well as being remixed for the theme of the Bridge of the Sages in Ocarina of Time.
 * Castlevania has the classic "Vampire Killer" tune which appears in some form or another in most of the games, though it has remained absent from many of the later ones. In general, the series loves this trope, with the Big Three recurring tunes being Vampire Killer (from the first game), Bloody Tears (from Simon's Quest) and Beginning (from Dracula's Curse). Once Theme of Simon was introduced in Super Castlevania IV, it started popping up a lot as well, even in games where Simon isn't present or even mentioned. Truely Wolverine Publicity in music form.

Adventure Game

 * Space Quest's title theme. A somewhat altered version was used in SQ IV and up.
 * One of the elevator muzak songs from Police Quest: Open Season was reused in Leisure Suit Larry 6, in the hotel lobby.

Beat Em Up

 * The Final Boss theme in the arcade game Teenage Mutant Ninja Turtles Turtles in Time was also used in Teenage Mutant Ninja Turtles III: The Manhattan Project for the NES, which came around the same time.
 * Although the first NES TMNT game doesn't use the full TMNT theme, it does use the "heroes in a half shell" riff from it.
 * Many of the Double Dragon games uses the same title theme. In fact, the few games that don't use the classic Double Dragon theme in some form or another tend to be the crappier games in the series (namely the arcade version of Double Dragon 3 and Double Dragon V). Super Double Dragon also uses the first stage theme from the original game in one level, while Double Dragon Advance has a soundtrack composed entirely remixes from the first two games (including the Final Boss theme from the second NES game, which is played when the player faces Raymond).
 * The Japanese version of Super Double Dragon actually plays the original theme on its title screen. The City Slum theme from the original was also remixed in SDD.
 * The PC Engine CD version of Double Dragon II, while otherwise regarded as the best version of the game, ironically lacks the classic theme tune.
 * In your Belief, the absolute Tear Jerker of an Award Bait Song from Asura's Wrath can be heard all of the place, such as the ethnic version of the theme, The Repirse of the theme, Vajra Asura vs. Vajra Deus and Bonds.

Driving Game

 * The title screen music of every Mario Kart game to date has contained a remix of the original Super Mario Kart theme.
 * In the first Twisted Metal, the main riff of "Asphalt Assault" recurs alot, most prominently in "Cyburb Hunt" and "Cyburb Slide".
 * "Quake Zone Rumble" is almost identical to "Snowblind" from Jet Moto.
 * The "Suburbs" music from Black is a remake of "Drop Dead" from the first game.
 * The strings riff from "Drop Dead" is reused in "The Drop Zone" in 2.
 * "Suicide Slide" sounds like a darker version of "Cyburb Slide", also using elements of "Drop Dead".
 * "Field of Screams" is a more rock & roll sounding remix of "Asphalt Assault".

Fighting Game

 * Geese Howard from Fatal Fury has a remixed version of his original theme song present in every game he appears in, with the title and instruments changing but the composition staying more or less the same. The title of the song is always something "for Geese" (Soy Sauce for Geese, A Kiss for Geese, A Stiff Shoulder for Geese, etc.). The lone exception is the Infernal Gate stage theme in King of Fighters: Maximum Impact, which is named "Kiss Geese Once More".
 * Similarly, the Fatal Fury games' other Big Bad, Wolfgang Krauser, appeared accompanied by an Ominous Latin Chanting excerpt from Mozart's Requiem, either "Dies Irae" or "Lacrimosa".
 * The King of Fighters uses "Esaka?" from the '96 game quite a bit, from its original use in that game to the remixes (actually used for the various Kyo clones) in '99 and '03.

First Person Shooter

 * Halo has its characteristic theme.
 * Many recurring themes abound throughout the trilogy, including "Enough Dead Heroes"(the middle section is often heard during battles with Hunters), "Brothers In Arms"(most notably in the third game), "Perilous Journey", "A Walk In The Woods", "Under Cover of Night"(one of the most common themes), "Shadows"(the Flood theme), "On a Pale Horse"(a variation of this theme is used in "Leonidas", ie the music during the gondola rides in Regret), "Broken Gates"(remixed in the Tsavo Highway mission as "Out of Shadow"), "High Charity", "Perchance To Dream", "The Last Spartan", the Delta Halo theme, and the Arbiter's theme.
 * Leonidas itself got an epicness upgrade in Halo 3 as Leonidas Returns. High Charity's Rue and Woe was remade as Heroes Also Fall in Halo 3, and Respite was remade as Tribute. Earth City, Orbital Drop Shock Trooper, and Unreconcialed all share the same format (strong opening, fast-paced supporting melody with powerful main melody, quietened down in the middle, reprise of main melody towards the end) and are all recurring themes in their respective games.
 * The opening cinematics of all three games feature a characteristic strings motif, which also appears in the intro to the Delta Halo level in Halo 2, and the Legendary ending of Halo 3.
 * "Unyielding", itself a recurring theme in part 2, is based on "Rock Anthem for Saving The World" from part 1.
 * As is the latter part of "Greatest Journey" from part 3.
 * In turn, parts of "Unyielding" were remixed in "One Final Effort".
 * The ending riff of "Brothers in Arms" recurs several times in Halo 2.
 * The first half of the song "Heretic, Hero" in part 2 uses both the motifs of "Truth and Reconciliation" and "The Gun Pointed At The Head of the Universe". The second half is "A Walk In The Woods".
 * The "Pursuit of Truth" movement of the High Charity suite is based on the song "Leela" from the Marathon 1 soundtrack (heard in the second level among others), the series that Halo is the Spiritual Successor to.
 * The last track of the Halo 1 OST includes a hidden easter egg, the Tear Jerker piece "Siege Of Madrigal" from the Myth games.
 * In Amber Clad, Unforgotten, and the beginning of High Charity Suite share a recurring slow strings motif.
 * "Finish the Fight" is a combination of the main Halo theme and "The Last Spartan".
 * "Dream Again" is "Under Cover of Night" done In the Style Of "Perchance to Dream".
 * "Farthest Outpost" uses the beat of "In Amber Clad" with the Ark theme.
 * The Myth series, also developed by Bungie and scored by O'Donnell, uses lots of recurring riffs.
 * Even Halo Reach subtly reprises many older motifs, such as "On a Pale Horse"(in "Noble Mission"), the Covenant/Arbiter theme (in "Inbound Imminent"), "Farthest Outpost"(in "From the Beginning" and "Sword Control"), "Destroyer's Invocation"(in "Aim to Please" and "War Machine"), "Ghosts of Reach"(in "The Battle Begins", "Make it Count" and "Shipbreaker"), "In Amber Clad" (in "Before the Fire" and "We Remember"), "Move On"(in "Breaking Point"), "Keep What You Steal"(in "Say the Words"), "Respite/Tribute"(in "Hymn for Reach"), "Enough Dead Heroes" (in "The Fall" and "Ashes"), and the original Halo theme (in "Immemorial", "Latchkey", and "Unreconciled").
 * The Medal of Honor series has these in spades; eg "Main Theme", "Locating Enemy Positions", "Attack on Fort Schmerzen", "The U-Boat", "Panzer Attack", "Rjukan Sabotage"(reworked for the first part of "Escaping Gotha"), "Nordhausen"(reprised in "Schmerzen" from Allied Assault), "May 10th, 1940"(the title theme of Underground), etc. In fact, most of Allied Assault's soundtrack is lifted straight from the first two games.

General

 * Nintendo composer Kazumi Totaka has hidden a short song in many of his titles, often in very obscure places.
 * The original Mario Party includes shout-outs to earlier games. The tracks "Slowly, Slowly" and "Dodging Danger" are based on the World 6 and 8 map themes, respectively, from Super Mario Bros 3. And the Magma Mountain course includes a section based on Bowser's Keep from Super Mario RPG.

Hack and Slash

 * Drakengard has a theme called "Growing Wings" which represents the series (all two of 'em) as a whole. A version of it is played when which is just heart-wrenching.

Platform Game

 * Several of the riffs from the Monty on the Run theme song are reused in Impossamole. In turn, the Bermuda Triangle and Ice Land themes in the Turbo Grafx 16 version use riffs from the title theme.
 * The Sonic the Hedgehog series has its classic theme song music from the first two games (which was mixed with "Hall of the Mountain King" and "Flight of the Bumblebee" for the syndicated cartoon), which was even referenced as late as 2001 in Sonic Advance. A bit more commonly, though, is the Round Clear music from ~Sonic 3 & Knuckles~, which has been used for over ten years when a character completes a stage.
 * It's also heard as Sonic's victory theme in Brawl.
 * Some Game Gear spin-offs had Sonic - You Can Do Anything from Sonic CD as an level theme or invincibility jingle.
 * The series also has its infamous Drowning Theme, officially called "I Wanna Breathe", that is guaranteed to appear in any Sonic game where you can go under water without instantly dying.
 * Sonic Adventures Twinkle Park/Circuit level reused the music from Sonic 3D Blasts Panic Puppet Zone.
 * Super Mario Bros. uses these liberally; it's very unlikely we'll ever see another game that does not contain the familiar World 1-1 music.
 * The "doo-doo doo doo-doo doo, doo" riff from the beginning of the World 1-1 theme is heard on the "star select" screen when Mario first enters a world in Super Mario 64.
 * The music for underground levels (from now on called "World 1-2" Music) is much more commonly remixed and reused; in Super Mario 64, it has several dynamic variations, changing as you go deeper underground.
 * This is taken to such extremes that the Super Mario Galaxy 2 Shadow Mario theme is a remix of a remix of a remix.
 * Super Mario Sunshine has an awesome moment where the first six notes are played on a heavily distorted guitar when Shadow Mario first appears.
 * The original Underwater music is often heard as well; notably, not often as an Underwater theme. First it was remixed as the title theme for Super Mario Bros. 2, from which it spread to the title screens of All-Stars and the Game Boy Advance games.
 * The Starman theme too. Although there aren't any invincibility star power-ups in Super Mario 64, it is used for all of the power-ups in that game. A metallic-sounding remix is used for the Metal Cap.
 * The "Peach's Castle" theme from Super Mario 64 is also frequently used, to a far lesser extent. Nearly every game that has a segment that takes place in Peach's Castle will use a variation on that theme, even as a simple cameo. It was even in the SNES game Donkey Kong Country 3.
 * Super Mario Kart's Bowser Castle courses use a remix of the Final Boss music from Super Mario World, and the Ghost Valley courses use the Ghost House theme from said game.
 * The 64DD expansion pack to F-Zero X had a remix of the Rainbow Road music from Mario Kart 64 for its track of the same name, in place of "Driving Through On Max" from the regular game.
 * Super Mario World remixed the Super Mario Bros 3 fortress music for the Valley of Bowser map.
 * Super Mario Galaxy has remixes of World 1-1 and World 1-2 (and a cameo of the underwater music) from the original game, the athletic theme and airship theme from Super Mario Bros. 3 and the Bowser stages from Super Mario 64.
 * Mario Kart Double Dash and Mario Kart 7's respective Rainbow Road music use part of said circuit's Mario Kart 64 theme. The Super Mario Kart Rainbow Road riff is used as the intro of many of the later Rainbow Road themes.
 * Bowser's Road (the theme for the Bowser levels in Super Mario 64) in general. It's been in Super Mario 64, Super Mario Galaxy, Super Mario Galaxy 2 and two Mario and Sonic olympic games already and possibly a few more not listed. Also, the main theme for Delfino Plaza in Super Mario Sunshine, Peach's Castle from Super Mario 64 (it's appeared in most Mario RP Gs and spinoffs in history now) and various others.
 * Most Mega Man games use variations on a four-measure riff (heard here) when a stage has been selected. As far as this troper can determine, the piece's name is "Robot Master Chosen."
 * Likewise, the jingle for defeating a Robot Master has appeared in most of the classic games.
 * Another example is Proto Man's Whistle, which heralds his appearance starting in Mega Man 3. It's even played with in 5:
 * To a lesser extent, there is the Mega Man 2 title screen theme, which shows up in some later games, usually during the credits.
 * The first three games of Mega Man Battle Network also use variations of the same main theme, which also made the occasional appearance in later games (such as in the credits music for 5). 5 also uses a variation of 4's theme.
 * The prologue sequence in Wonderboy III: The Dragon's Trap reprises the final dungeon music from Wonderboy In Monster Land. The cave music from the arcade version of WBML also returns at one point.
 * The Kirby series has several of these, most notably Green Greens, Gourmet Race, and King Dedede's Theme.
 * The original Kirby's Dream Land title screen music appears to be getting more use these days (it showed up in Kirby Super Star Ultra and Super Smash Bros Brawl's "Butter Building" music, among other places). As well, each game uses some variation on the classic death theme, with varying degrees of disguise.
 * The "Stage Clear" theme (also known as the Kirby Dance jingle); a variation on the general melody appears in every Kirby game.
 * In Kirby Super Star in particular (and its remake), there's one recurring riff which is heard in various songs, the most glorious example being during the destruction of the final boss (and his Cosmic MacGuffin).
 * In Kirbys Epic Yarn, an 11-note motif is heard in many songs in the game.
 * A song originally used in the Boss Rush of Kirby's Dream Land shows up as the Choose Weapon theme in Kirby Super Star, the Sound Test theme in Kirby's Dream land 3, the Enemy Info theme in Kirby 64 The Crystal Shards, and finally the Boss Game Select theme in Kirby Canvas Curse.
 * In the Contra series, the "Stage Clear" jingle from the first game and the "Game Over" jingle from Contra III are frequently reused. Shattered Soldier's fifth mission features a remix of the first game's first stage music.
 * Cross series: The "Battle Train" and "Mr. Heli Robo" musics have the same beats as "Look To The Sky (True Color Mix)" and "Dynamite Rave (Down Bird SOTA Mix)", respectively, from Dance Dance Revolution. All were produced/remixed by Sota Fujimori.
 * In the Metroid series, Brinstar's theme is in common use, Samus' theme has been in nearly every game since Super Metroid, all the various Brinstar themes were in Metroid Prime 2: Echoes as multiplayer songs, and finally, Crateria's theme was used in in Metroid Prime 3.
 * There's also the 13-note "item obtained" theme, and the "game start" theme, as well as the "Chozo statue room" theme (which is mostly electronic beeping). Most of all however, is the title screen theme from the first game.
 * The Lower Norfair theme from Super Metroid is also used for Magmoor Caverns in Prime.
 * The Naughty Dog Crash Bandicoot games repeat Dr. Cortex's and N. Gin's Leitmotifs.
 * All recurring bosses have their themes remixed throughout the original trilogy (this is kept in The Huge Adventure/XS as well, albeit mixing up the roster each theme plays for). The Warped title theme is also remixed into several later titles, acting as a Bootstrapped Theme of sorts. The Twinsanity theme is also reused in numerous segments of Crash Tag Team Racing.
 * Tomb Raider III reused several music themes from the first game; eg a music used in St Francis Folly was remixed Indian style for the India Jungle level. Also, the recurring title theme.

Puzzle Game

 * Several tunes in Katamari Damacy, most notably the main theme, "Katamari On The Rocks".
 * "The Game" from The Seventh Guest and The 11th Hour. Most of the characters' leitmotifs are variations of this riff. There are also a few other recurring themes, like the Ominous Music Box Tune(heard in the mouse puzzle and the tower), the library theme and the Stauf Train theme in T11H
 * Professor Layton has the Puzzles theme. It was played during puzzles for the first two games, but after the melody is replaced in Unwound Future, it is moved to the respective Puzzle Keeper's house (Beasley, Puzzlette, Keats, etc.). It's also used in the bonuses menu of Last Specter.

Real Time Strategy

 * Command and Conquer Red Alert has the Hell March tune. The Tiberium universe, on the other hand, tends to use snippets from Act On Instinct and Industrial.

Role Playing Game

 * The Pokémon games use this in extremes; background music such as defeating a Trainer, the Gym interior, etc. are rearrangements. Not to mention the original games' opening/title screen music showing up in various places, including the Champion/Mt. Silver battle of Gold/Silver/Crystal.
 * To list every riff would take a lot of time, but in one of the stranger examples, Pokémon Pinball's Blue Field theme was rearranged as the more relaxed motif of Ecruteak and Cianwood in Gold, Silver and Crystal.
 * Most themes change from game to game. The Pokémon Center music, however, is always a variation on the same theme, as with the Gym interior and title screen themes.
 * The themes from the various Battle Towers tend to be a remix of the original Battle Tower music from Pokémon Crystal.
 * The Ear Worm-y music that plays when someone is bringing you somewhere to show you something (known as "Follow Me" or "Guidance" in the games; "Silly Psyduck" in the anime) is always a variation on the same theme.
 * Not to mention, this version used in Pokemon 2000.
 * The Final Fantasy series has a number of these.
 * Tied for most famous are the "Prelude" (or "Crystal Theme") and the series's main theme, "Final Fantasy" (aka "Prologue" or "Bridge Crossing Theme").
 * Notably, the main theme is missing from most of Final Fantasy VI... until it appears as a Triumphant Reprise of sorts just before The End.
 * Right behind those are the victory fanfare and the Chocobo theme (all its variations are named "X de Chocobo"). All four tend to be subject to minor tweaks per game, but are still recognizably the same tune.
 * In addition, almost all of the battle themes share variations on the opening bass riff, but they all diverge from there; noticeable stylistic similarities exist between many of them, though, particularly those composed close together.
 * After being absent for most of Final Fantasy VIII, said bass riff finally does appear for the final boss music.
 * Like Zelda, Final Fantasy has a jingle for obtaining key items, though mainly used in the older games.
 * The thematic Chrono Trigger theme is reused several times in Chrono Cross, as well as Lucca's victory fanfare theme. In addition, CC's theme for bustling Termina is reminiscent of Guardia's Millenial Fair in CT, and In addition, since CC started life as a game called Radical Dreamers, many themes from the original Satelliview game are remixed for CC, including the main theme, the battle theme, "Frozen Flame", and "Star-Stealing Girl".
 * The Ys series has several recurring riffs, for example, "Adol's Theme", which is one of the opening musics for Ys Book I and II, recurs in some of the dungeons of the other games (eg. the Canal in Ys II, Mountain Shrine in Ys IV, the stage entrance and Ilbern Ruins musics in Ys III, and the ending of Ys V), and the Ys IV overworld theme not only has many variations in its titular game(Field, Great Forest of Selceta, Blazing Sword, Beyond Reminiscence, Valley of Quicksand, etc.), but in Ys VI as well(Release of the Far West Ocean, Windslash Steps, Mountain Zone, which also partly sounds similar to the Solomon Shrine music in Ys II, and Defend And Escape! (when you escort Olha and Terra out of the Romun ship), which also resembles part of Niena's theme from Ys V, and the latter part of "Field Of Gale" in Ys V. "Overwater Drive", heard in the Limewater Cave in Ys VI, is roughly a remake of "Beat of the Terror", the Abandoned Mine music in Ys I and II. The motif during the cutscene where the Ark of Napishtim is revived recurs during the second half of the final boss battle(The Depth Napishtim), as well as in Defend And Escape!.
 * The boss themes "Holders of Power", "Protectors", and "Shock of the Grim Reaper".
 * "Armored Bane" reprises the riff from "Battle Ground" and "Over Drive".
 * Earth Bound Zero introduced several themes that appear elsewhere in the series - "Pollyanna (I Believe in You)", "Eight Melodies (Queen Mary's Lullabye)", "Humoresque of a Little Dog", and the theme to the New Age Retro Hippie. Earthbound also introduced "Eight Melodies (Sound Stone)", which was also reused multiple times (including being remixed with the first "Eight Melodies" tune to make "Sixteen Melodies" in Mother 3).
 * Practically every major tri-Ace game (Star Ocean, Valkyrie Profile) contains a bonus dungeon with the theme music "Journey to the Deep Space". Several iconic battle themes can also be heard across games, such as the battle theme from the first Valkyrie Profile.
 * Kingdom Hearts II reuses all the exploration and battle themes of the original's worlds that also appear in the sequel.
 * All of Organization XIII's themes in Kingdom Hearts II contain a piece of the Organization's main theme, "Another Side." These pieces have been collected in to an orchestrated work called "The 13th Anthology".
 * Dearly Beloved.
 * "Destati" is used and remixed repeatedly throughout the series as well.
 * Almost every Dragon Quest game has the same introduction music, as well as the same "item found!" five-note tune.
 * The Saturos theme for Golden Sun, which, as of Dark Dawn, seems to be becoming the Bonus Boss battle music.

Shoot Em Up

 * Gradius has "Aircraft Carrier," which is originally used for boss battles in the first Gradius game, and is used for the wave of item-carrying Zubs that appear before a Boss Rush in subsequent games.
 * When fighting a boss returning from a previous game, the boss music from that game is usually used, eg "Poison Of Snake" for Salamander/Life Force bosses, "Take Care" for Gradius II bosses, and "Dark Force" for Gradius III bosses. Exceptions include the Boss Rush in Gradius IV, which all use the "Take Care!" music from Gradius II regardless of their game of origin, and the reappearance of the Rolling Core in Gradius V, which uses "Aircraft Carrier" instead of the Gradius IV boss theme.
 * The first stage music from R Type and R Type 2 are both remixed in R Type 3, and Delta.
 * Most of the BG Ms from Raiden II were remixed in Raiden IV, including "Repeated Tragedy", "Tragedy Flame", "All or Nothing", "Depression", and "Flap Towards The Hope".
 * All Windows generation Touhou games have more or less the same riff for the menu screen. It even extends to some fangames (namely Concealed the Conclusion).
 * Scarlet Weather Rhapsody has a very distinctive riff that plays in some fashion in every single song in the game that isn't a battle theme (so, the opening theme, the title, every pre-battle sequence, the credits...)
 * Most Compile shmups, from Gulkave (one of their few Horizontal Scrolling Shooters) to The Guardian Legend to Gun Nac to GG Aleste II to Zanac Neo, play the same jingle when you get enough points for an extra life. This sound can also be heard in some of their more casually-oriented games.
 * Compile's 16-bit shmups generally used a different extra life jingle, which can be heard in Musha Aleste, Robo Aleste and the PC 98 Disc Station game Rude Breaker.

Sports Game

 * The riff of the Skate Or Die theme song ("SKATE OR DIE! DIEDIEDIEDIEDIE!") recurs in several variations in the second game (eg the mall theme, at least one of the cutscene musics).

Stealth Based Game

 * The Metal Gear series did not let the "Operation Intrude N313 ~ Theme of Tara" piece die. It's first heard in the original Metal Gear as Snake comes up from the water and begins the mission, and while the N313 fanfare only plays once in the whole game, the piece tends to be treated as an amalgam. Later sightings -
 * There's a comical mix of "Theme of Tara" during the indoor infiltration segments in Snake's Revenge, all the more unusual because it was for the NES, and the NES version of Metal Gear featured a completely different infiltration theme. The TX-55 Metal Gear theme from the first game is also used in the attract mode and when Snake faces the new Metal Gear at the end of the game.
 * Metal Gear 2 used a squint-and-you'll-hear-it mix of the "Theme of Tara" in the background to some of the sneaking stages.
 * Also, "Killers", "Night Sight", and "Big Boss" shared the same or a similar riff, "The Front Line" and "Level 1 Warning" are remixes of "Advance Immediately" (which itself resembles the first game's alert theme), and "Mechanical" is a remix of Metal Gear 1's boss theme.
 * Metal Gear Solid and Metal Gear: Ghost Babel used it as the backdrop to the VR Training missions with the "Opening Intrude N313" fanfare playing over the briefings. In Ghost Babel, the music played as Snake parachutes into the jungle is a mix of the Opening Intrude N313 fanfare, directly paralleling his previous entry to the same fortress (the plot revolved around him re-infiltrating the building that had once been Outer Heaven).
 * Metal Gear Solid 2: Substance used the Intrude fanfare/Theme in VR, when playing as Snake in his MGS1 costume. Pay attention during the "Opening Infiltration" segment of Metal Gear Solid 2, and you'll hear a little nod to the Fanfare as Snake lands on the Tanker.
 * In Metal Gear Solid 4, the music that plays while Snake stalks the Resistance member is a heavily modified mix of Theme of Tara. It's also possible to hear sounds of the original Theme emanating from a house - someone appears to be playing the original Metal Gear and really failing at it.
 * In Super Smash Bros Brawl, it's one of the songs initially available on the Shadow Moses stage, complete with the Fanfare lead in. It also plays over Snake's introduction in the Story mode.
 * "Zanzibar Breeze", a track first heard in Metal Gear 2 over the opening movie, reappears a lot, usually as an Easter Egg. In Metal Gear Solid, a mixed version of the opening bars was used as the Main Menu theme (it also showed up as an Easter Egg in Metal Gear Solid Integral). It showed up again in Metal Gear Solid 4 as an Easter Egg track on the iPod.
 * Metal Gear Solid: VR Missions also feature plenty of remixed versions of music from the first two MSX2 games. Metal Gear Solid: Integral also features a remixed version of the "Theme of Solid Snake", in addition to "Zanzibar Breeze", as an easter egg via Codec.

Survival Horror

 * The music from the first chapter of House of the Dead 1 returns in Chapter 2 of HotD2, and the Final Boss Magician's theme from the first game is reused for his reappearance in Chapter 5.
 * Many songs in the Silent Hill games (Theme of Laura, I Want Love, Your Rain, Waiting For You, etc.) feature a guitar riff from the latter part of the opening theme of the first game. Variations of this theme occur in the Tear Jerker scenes with Lisa in SH1(Not Tomorrow) and Angela in SH2(Theme of Laura Reprise).
 * "Home Town", the ending theme from Silent Hill 3, is a vocal version of the opening theme from SH 1.
 * "Dance With Night Wind" in the third game resembles "True" from the second game, and both are Tear Jerkers.
 * "Promise" in SH2 is another pastiche of the SH1 theme, and is in fact used as Alessa's theme in the movie.
 * The intro of "Sickness Unto Foolish Death" from Silent Hill 3 is reused in The Room whenever Henry returns to the apartment from the otherworld.
 * A melodic line from the guitar solo in "I Want Love (Studio Mix)" from the Silent Hill 3 soundtrack shows up again in "Your Rain" from Silent Hill 4 and "Hell Frozen Rain" from Silent Hill: Shattered Memories.
 * On a similar note, a melodic line from "Theme of Laura" also appears in the second solo of "Waiting For You" from SH4.
 * A variation of the "White Noiz" motif from Silent Hill 2 is used in "A Stray Child" in Silent Hill 3.

Third Person Shooter

 * The Syphon Filter games have a memorable title theme(the Omega Strain version is the Crowning Music of Awesome), along with several recurring in-game motifs. The title theme motif recurs the most in the PS 2 games.
 * The Pharcom Expo Center music from the first game, and its "danger" variation, are reused when you revisit the center in Syphon Filter 2.

Turn Based Strategy

 * Fire Emblem has a title theme and an Encounter-ally/Recruitment theme, the latter recently known as "Together We Ride", in most of its games.
 * "Together we Ride" is not the Encounter theme in Path of Radiance, but it does appear during one dialog between Kieran and Elincia combined with "Knight's Oath" a secondary recruitment theme used throughout the seris.
 * Fittingly enough, the theme used for the Fire Emblem characters in Super Smash Bros Melee was a combination of these two themes.
 * The Super Scope shooter Metal Combat, the sequel to Battle Clash, uses the level-up jingle from the Fire Emblem series when you complete a training stage. Intelligent Systems, the makers of Fire Emblem, also made the Battle Clash games. Ironically, Metal Combat only came out in North America and Europe, and during a time where none of the Fire Emblem games were released internationally.
 * Many Nippon Ichi games (Disgaea, and Makai Kingdom especially) will use music samples from La Pucelle, particularly the Rosenqueen Shop and Dark World themes, in various situations

Visual Novel

 * The Ace Attorney series has a bunch of songs that can accompany its courtroom drama, but when it really counts, they use the first game's crisis theme, "Investigation ~ Cornered".
 * Search - Core 2001 has appeared throughout the series whenever Phoenix discovers crucial piece of evidence during investigations.
 * The suspense theme played several times throughout the first three AA games, was replaced in the fourth, only to come back in the fifth.
 * Many tracks in Ace Attorney Investigations: Miles Edgeworth contain portions of the song "Great Revival ~ Miles Edgeworth," which originated in the second Ace Attorney game. Rather appropriate, considering he is the main character.
 * The composers for the Umineko no Naku Koro Ni Visual Novel use this quite often. zts is quite notable for using this; for example, parts of goldenslaughterer have been reused for dreamenddischarger, resurrected replayer, and the_executioner. The aforementioned resurrected replayer also reuses a part of far.

Anime and Manga

 * The instrumental version of "Ai o torimodese" that plays when Kenshiro launches a major attack in Fist of the North Star is practically an anthem for Fighting Series as a whole.
 * The very final episode of the original anime series (well, the sequel series actually) features a medley of all the vocal opening and ending themes that were ever used on the show.
 * Digimon Adventure, Digimon Adventure 02 and especially Digimon Tamers all did several takes on their opening themes for use as background music, more often than not with a more melancholic bent, with the Tamers theme in particular lending itself very well to this and getting more such takes of it done; Digimon Xros Wars did the same for a piece of music which, while a definite leitmotif for the series, is not either of its opening themes.
 * Amazingly, Azumanga Daioh uses this: While the opening and ending themes are for the most part played only during the opening and ending sequences, you're gonna be hearing "Saa, Hajimari You" (AKA: the middle and end-of-episode preview theme) or "New School Term 6" somewhere in the music. And once you've heard them, you'll recognize them showing up all over the place.
 * In Kore wa Zombie Desu Ka, the first 10 seconds or so of Kumori Nochi Hare seems the find its way into almost every background music played in the anime in some form or another.

Film

 * Known through Pop Culture Osmosis to nearly the entire planet, The Good the Bad And The Ugly has a recurring riff that will live on forever as the sound of the western, aa-AA-aa-AA-ahhhh.
 * Every Back to The Future movie used similar instrumental music when replaying scenes from different perspectives (such as the lighting hitting the DeLorean at 88 MPH from the first movie, which is replayed at the end of the second and consequently the beginning of the third).
 * Star Wars and Indiana Jones. The former also has its famous Imperial March, better known as the theme of Darth Vader.
 * Star Wars uses this a lot, despite many themes apparently being intended to mainly represent specific characters. The "Main Theme" was originally meant to be Luke's theme, but was used as this less and less as the series went on. In The Empire Strikes Back, Yoda's theme is often used at seemingly unfitting times. The original film uses Princess Leia's theme at odd points as well, such as when Obi-Wan dies.
 * "He's a Pirate" from the Pirates of the Caribbean series, has been featured in almost everything related to it, from all three films, to being the battle music in the Pirates themed world in Kingdom Hearts II, to playing in the queue for the original ride.
 * Chico Marx's theme appears in several Marx Brothers movies, including Harpo's solo in Monkey Business and Chico's endless piano solo in Animal Crackers. It even has two different Forgotten Theme Tune Lyrics ("I'm Daffy Over You" and "Lucky Little Penny").
 * The Toy Story series tend to use riffs of "You've Got a Friend In Me", and the third also uses riffs from "When Somebody Loved Me"
 * Aladdin has an ongoing theme in "Arabian Nights", "One Jump Ahead", "Friend Like Me", "Prince Ali", and the Cut Song "Babkak, Omar, Aladdin, Kassim".

Live-Action TV

 * Doctor Who has used variations of the same theme song since 1963.
 * The new series went on to use it as a basis for several character themes (notably the Doctor's, while the "sound of drums" heard by the Master is the main melody from the theme itself.)
 * A rare CD of Doctor Who music was once released, entitled "Variations On A Theme". Guess what was on it. On every track.
 * Red Dwarf's first season uses pretty much remixes of the closing theme as the only pieces of music. It's actually quite aggravating.
 * Another non-game example: the "Life and Death" theme from Lost, which has been used since the first season every time a character dies.
 * There is also music related to the freighter that plays several times during seasons 3 and 4, with an action packed variant playing at the very end of the season when . However, for some reason, the theme continues being used in season 5, suggesting it is becoming some kind of general action music.

Music

 * Classical music example: Four different works by Beethoven use the same original theme: the ballet The Creatures of Prometheus (Op. 43), No. 7 of the Twelve Contredanses (WoO 14), a set of variations for piano (Op. 35), and the finale of the "Eroica" symphony (Op. 53).
 * Sound Horizon uses recurring riffs as an indicator that certain songs (often on separate albums) are connected to each other in some way (such as suggesting that the Rose Princess's abandoned child from "Bara No Tou De Nemuru Himegimi" is Lafrenze from "Majo to Lafrenze", or that Michelle Malebranche from the cage trilogy is responsible for Hiver's inability to be born into the world in Roman).

Web Comics

 * Parts of "Sburban Jungle", "Descend" and "Black Rose/Green Sun" pop up a lot in Homestuck's extensive library of music.

Action Adventure

 * The game Ni GHTS: Journey of Dreams does this with the main theme....a lot. The song occurs at least a dozen times. Once of the girl main character, once for the guy main character, twice for a duet between the two, once for the final stage, once for each of the four multiple endings, etc.
 * Each separate stage in the worlds will use a different mix of that world's theme song.
 * Along with the boss-fights having re-mixes for the second go at them.
 * Overlord uses its main title theme liberally throughout the soundtrack. The remix used for the final boss of the first game is particularly epic.
 * Every song in ~Luigi's Mansion~ is a variation on the Mansion theme.
 * Aquaria does this. There are at least five "different" tracks on the soundtrack that are slight variations on a basic (gorgeous) theme, and two or three really different tracks that still work in elements. There's one particular motif which is worked into so many of the songs because it has gameplay significance.

Adventure Game

 * The Journeyman Project has several variations of a recurring theme; a new-age version during the opening sequence, an "elevator muzak" version in the apartment hallways, an orchestra version when you first arrive at the TSA, and a rock version during the credits.
 * In Flower, one motif is seen in almost all songs.

Driving Game

 * Mario Kart DS does this with a lot of its track themes using riffs from the title screen music.
 * In Twisted Metal: Black, the melody of The Rolling Stones' "Paint it Black" pops up at several points in the soundtrack. Blink, and you'll miss it.

Edutainment Game

 * Oregon Trail II uses many variations of its Title Theme Tune, for the town you start in and certain sections of the trail.

Fighting Game

 * Super Smash Bros Brawl has a good deal of its original music based around an orchestral piece composed by Nobuo Uematsu, which has lyrics written in Latin.
 * Melee did the same thing, with a tune that sounds similar to Bowser's theme from Super Mario 64. It shows up predominantly as the Menu theme, but can also be heard in Multi-Man Melee modes, and boss battles. Melee's own opening theme shows up in some tracks as well, with the alternate menu music, some event matches, and an alternate track for Final Destination.
 * The soundtrack of Soul Calibur II does this a lot, and several tracks (If There Were Any Other Way, for example) carry over to Soul Calibur III.

First Person Shooter

 * Negative example: One of the criticisms for the Halo 3 soundtrack was the repetition of the piano theme from the debut trailer.
 * AKA "Finish the Fight".
 * Especially during the Covenant mission.
 * There's also "Truth's theme", "Farthest Outpost", and a few shorter themes.
 * Turok 2: The River Of Souls and Lair Of The Blind Ones musics are both somewhat based on the main title theme, the Death Marshes theme uses riffs from both the Hub and Save Room musics, and the Lightship music in turn reuses a hook from Death Marshes, as well as the Oblivion Portal theme in its latter half.
 * Halo 2: a variation of the opening riff of "Blow Me Away" is heard during the sniper alley sequence in Outskirts. Blow Me Away proper, of course, is used during the Mausoleum battle in Gravemind.
 * "Unyielding/Reclaimer", a variation of the Halo theme with a characteristic piano hook, recurs at least twice in the game.
 * Deus Ex and The Nameless Mod both have their main theme pop up in various parts of the sound track.
 * Action Doom II: Urban Brawl has one of these. It first appears at the very beginning of the intro theme, then (if you're going the good way, because there are multiple paths through the game) pops up in first stage intro, bar music, end of the final level music and (in a warped form) the final boss theme, until it finally (hopefully) returns at the very end of the good ending theme.
 * Marathon 1 used a recurring theme in "Landing", "New Pacific/Reprise", and "Rapture". The melodic theme of "Flowers in Heaven" is reprised in "Splash (Marathon)" during the final stage. Also, "Guardians" and "What About Bob?".
 * Medal of Honor: Frontline, in addition to the themes from the first game, features:
 * The middle of "Operation Market Garden", the first part of "Border Town", and Patterson's theme (appears throughout the soundtrack)
 * "Shipyards of Lorient" and the third part of "Escaping Gotha"(played during the final confrontation with Sturmgeist)
 * The climax of "Border Town", and "Emmerich Station/Thuringer Wald Express/Sturmgeist's Armored Train"
 * "Manor House Rally" and "The Halftrack Chase"
 * "After the Drop", the last part of "Kleveburg", and "Approaching the Tarmac/Clipping Their Wings"
 * "Nijmegen Bridge" and the first two parts of "The Rowhouses"
 * "Immemorial", "Remember Reach", "The Fall", "The Battle Begins", "Lone Wolf", "Distress", "Free Fire Zone", "Latchkey", "Return", etc. in Halo Reach.

MMORPGs

 * Runescape has some riffs and melodies that occur in various different pieces of song, like Runescape's main theme.

Platform Game

 * Sonic the Hedgehog again; often, the various in-game jingles (Invincibility, Speed Up), the menu screens, some specific cutscenes, the title screen, and recently the final boss all match the same theme, but with variations.
 * The original Sonic Rush took this to extremes; there's only ten-odd songs, one for each stage and a few for the boss fights, but the majority of the rest of the game's soundtrack is just rearrangements of those tunes. So, you'll be hearing "What U Need" a lot earlier than the level it's featured in, as it's also the Main Menu music.
 * Much of Sonic Adventure 2's soundtrack is built around a single motif, which finally comes to a head with the song "Live and Learn" during the game's final boss fight. It's pretty sweet.
 * Sonic 1 uses a scary remixed version of the main boss theme (Robotnik's Leitmotif?) for the final battle, as well as the cutscene at the end of Scrap Brain Act 2 where Robotnik drops you down the Trap Door.
 * The boss music in Sonic 2 also seems to be loosely remixed from the Sonic 1 boss theme.
 * ...which, in turn, was remixed and used in the final boss for that game.
 * In fact, although it had a different composer, the first half of the S3&K main boss music is a Musical Pastiche of Sonic 1's boss theme, more resembling the Final Boss remix of it. May be considered The Jimmy Hart Version.
 * In Super Mario World pretty much every single stage music is the same song, altered slightly.
 * Same goes for Super Mario Sunshine.
 * And Super Mario 64. And New Super Mario Bros., to a lesser degree. Don't forget Super Mario Land 2 for the Game Boy. And Yoshis Story, Heck, even Yoshis Island DS. Super Mario Galaxy stands out as the biggest post-NES Mario game that doesn't do this, and even there, several of the musical pieces have a similar recurring segment.
 * In the NES version of Bionic Commando, the main riffs of the Area 1/3/4/7(Bionic March) and Area 5/6/10 musics have a common theme. Same chord progression/bassline, but different melodies. The Area 1/3/4/7, Area 8, and Area 12 themes are remixes of the Stage 2, 4, and 5 themes respectively, from the arcade game.
 * Mega Man 9 has several of its BGM tunes use a recurring riff based on its title theme.
 * 4 has several variations on a five-measure riff in some of its stage themes - to wit, Ring Man's stage, Dust Man's stage, Drill Man's stage, and the first two Cossack stages.
 * Ditto for Snake Man's and Spark Man's themes, possibly others, in 3. Another recurring theme is used in the Wily Stage musics.
 * 5 has one in the Gravity Man, Napalm Man, Charge Man, and Proto Man's Castle stages, et. al.
 * In Zeta's World, same thing.
 * NES game Predator, same thing too.
 * The theme from Crash Bandicoot 3: Warped's hub appears several times in bonus stages, as well as the title screen.
 * In Crash Team Racing, the opening theme has five variant themes for each of its hubs, from the tropical beach to the frozen wastes.
 * Donkey Kong Country 2 has the title theme developed into the boss theme, Klubba's theme, and the theme for levels atop ship rigging.
 * Tomb Raider 3 has several of these, eg the opening and title theme motifs. Legend has a recurring One Woman Wail and "Ave Maria" motif.
 * Rayman 2 has one which is played constantly. You hear it every time you die, and almost every song starts with it. However, there is no actual song from which all the others are borrowing, it's simply a few notes which most of the songs use.
 * Tower of Heaven has one motif going through all the songs.
 * Tumblepop, an arcade game, is the same example as Punch Out below. The main theme is always the same, but remixed every time according to the countries the player is traveling to: with oriental instruments for the Japanese stages, percussions for the Brazilian ones, chimes for the Antarctic ones and so on.
 * Super Ghouls 'n Ghosts features thematic links between the six stage music tracks and the corresponding six (non-final) boss music tracks, apart from the tracks for Stage 3 (which is instead thematically linked to the Stage 5 boss music) and Stage 5 (which shares melodic elements with the Stage 3 boss music).
 * Same for the original Ghosts N Goblins.

Puzzle Game

 * Katamari Damacy remixes the main theme many times in each game. The second game even featured a version sung a capella by cats and dogs.
 * The song Cara Mia, better known as plays a few times throughout Portal 2.
 * First, it plays when you approach a Companion Cube.
 * Then, a minor key version is sung by
 * Finally, it shows up in its full operatic glory at the end of the game, sung by
 * Of course, if you listen real closely, you can hear bits of it in the Variable Mix that comes up when you use a puzzle element in the early stages.

Real Time Strategy

 * Dawn of War II likes using the "Dark Future of War" theme. For example, the part from 1:35 to 1:50 is used as the "mission complete" jingle and the melody (especially the four notes at 1:45) can be heard in the planetary map background music.

Role Playing Game

 * Earthbound has a downright creepy sequence of notes that plays in various locations and battles.
 * Mother 3 also has Tazmily's theme and it's "Love Theme", both of which reappear throughout the game to great effect. Particularly jarring is the penultimate appearance of the love theme, which is The Pigmasks' theme also shows up in a ton of different variations.
 * Even the Tazmily theme is a remix of the Hotel music from Earthbound, although it'll take you a while to notice it.
 * Don't get me started on Mother 3's soundtrack. It would be more expedient to list the songs that aren't recurring riffs.
 * Any individual Final Fantasy game contains several leitmotifs. You can hear some recurring tunes in Final Fantasy IV (such as the overworld theme and the "Red Wings" theme (which, for example, furnishes the "X joined your party!" riff)), but it's more prominent in Final Fantasy V, Final Fantasy VI (where the main theme of the game is basically also Terra's Leitmotif, and Final Fantasy VII (which literally has a soundtrack entry called the "Main Theme"; if you don't know what I mean, try singing "do re mi ti la").
 * If there's a vocal track in the game, you can expect to hear several versions of it, often considerably altered.
 * Final Fantasy IX has perhaps the most extensive use of this, for example:
 * Variations of Melodies of Life show up in at least eight places: it occurs briefly in "Memories Erased in the Storm", it's the main theme of "Stolen Eyes", it's part of the overworld music "Crossing Those Hills", Dagger sings it "Song of Memories", it's the main theme of "At the South Gate Border", it's "Garnet's Theme", it shows up in the ending in "Towards That Gate", and you have the full version in the end credits "Melodies of Life" (which eventually changes into the "Final Fantasy" music).
 * Not to mention a pipe organ version that plays while Steiner is hiding Garnet in a bag, a high speed version that plays during the beginning scenes and the remix used for the FF IX Coca Cola ads. The game also has the Burmecia theme appear in at least three different versions, both sad and dramatic versions of Beatrix's theme, and instances of music from other games in the series.
 * One scene had Melodies of Life played over Eiko's (melody-lacking) theme. As Melodies of Life is properly Garnet's theme, and the scene in question involved both Eiko and Garnet, this makes a certain amount of sense.
 * The 'World' Theme that plays during in the video sequence in the title screen "The Place I'll Return to Someday" eventually appears in the game itself in "Oeilvert", "A Transient Past", "Ipsen's Heritage", "The Four Medallions", and "Terra".
 * The 'Action' Theme that plays during the fake sword fight "Vamo' alla flamenco" early in the game, reappears in "Limited Time", "Rose of May", "Black Mages' Theme", "Protecting My Devotion", "Terra", "You're Not Alone!", and "Passing Sorrow".
 * A particularly good Final Fantasy example is the thirteen or so different versions and variations of Hymn of the Fayth from Final Fantasy X.
 * Not to mention fully ten variations of Suteki da Ne five of Seymour's Theme, and four of To Zanarkand (which takes on a whole different character as Revealed Truth).
 * Final Fantasy VII Crisis Core follows this example, with nearly every track that isn't a remix of a FFVII song being based around the same theme. Including the final boss music. In the original Final Fantasy VII, the main theme appeared as a recurring riff as well.
 * Fragments of Final Fantasy VIII's Ominous Latin Chanting orchestral opening piece Liberi Fatali are re-used in battle themes, background music and cutscene themes.
 * Final Fantasy X: Three main themes (To Zanarkand, Suteki da Ne, and Sight of Spira) that are reheard multiple times, culminating in the awesome credits music.
 * Super Mario RPG features a multitude of variations on Geno's theme song, from the cutscene in which he is introduced to the last bit of the ending. The Mushroom Kingdom theme song is also used to a lesser extent.
 * The arrangement of Bowser's Keep repeats a segment of the opening battle with Bowser (itself an arrangement of the final battle from Super Mario Bros 3).
 * Super Paper Mario has two songs that get a lot of mileage throughout the game as well (especially towards the end), the Memory theme and the Main Theme fanfare.
 * Fun fact: even Count Bleck's leitmotif is a variation of the Memory theme, it follows the same chord progression at the beginning if you listen, (and could probably also count as a Musical Spoiler once more of the story is revealed.)
 * Azure Dreams uses multiple remixes of the tower theme as you ascend (PlayStation version only; the Game Boy Color version's tunes are distinctly different).
 * As mentioned above Mega Man Battle Network uses its main theme in many parts, most noticeable being the "Heroic theme" and the Final boss areas.
 * Planescape Torment has three musical themes that are used in a number of variations (and sometimes combined together) throughout the game's soundtrack.
 * The later Wild Arms games (3-5) overuse this trope incessantly, to the point where almost a third of the admittedly enormous soundtrack consists of remixes or variations on previous tracks.
 * In fact, practically every Japanese RPG will fall prey to this, at the very least remixing its main theme three or four times. Examples include Chrono Trigger, Bahamut Lagoon, and Vagrant Story.
 * The Force Unleashed reuses its main melody on occasion, usually during a Crowning Moment of Awesome.
 * The soundtracks to the Knights of the Old Republic games have similar riffs, such as the "Sith Theme" and a lot of the music in KOTOR II.
 * Many songs in Suikoden V use one of two riffs--a fairly upbeat one from the world map theme and a melancholy one that appears primarily in cutscenes. The former riff in particular shows up all over the place.
 * Ys IV(some of which were mentioned in the "series" section):
 * "Field", "Forest of Selceta", "Beyond Reminiscence" and "Eldeel"
 * "The Dawn of Ys" and "Temple of the Sun"
 * "Battle 58", "Lava Area/A Kiss from Eldeel", and "The Heat in the Blaze"
 * A large fraction of the music tracks in Xenogears are spun in some way from the theme that plays most frequently when you are aboard the Yggdrasil.
 * Starting with Morrowind when Jeremy Soule came aboard as composer, The Elder Scrolls has had what has become known as the "Elder Scrolls theme". It tends to show up in at least two or three music tracks per game, including the main menu theme.

Shoot Em Up

 * Zanac, one of the first games to feature recurring riffs in its soundtrack. The music itself was ahead of its time too. Recurring motifs include the title theme and the first stage music.
 * Radiant Silvergun's songs use the same "Tadadah tadadah! Tadada tatadaa!" motif in almost every song.
 * Its Spiritual Successor Ikaruga has much of its soundtrack consisting of various remixes of Ideal. Nobody particularly minds the repetition.
 * The only music in that game that doesn't use any recurring riffs is "Faith".
 * R Type Final: The music to Stage F-B is an extended reprise of the Title Theme Tune.
 * The main riff of Raiden IIs Stage 1 theme ("Repeated Tragedy") is reused several times, eg in Stage 3("All or Nothing"), Stage 4, and Stage 7("Flap Towards The Hope").
 * Star Fox has at least three recurring riffs: the select screen and Stage Clear themes, the planet themes, and the Sector X, Asteroid Field, and Space Armada themes.

Simulation Game

 * Every Ace Combat starting with 04 does this often. Ace Combat 6 has three different recurring themes, with at least one of them being present in roughly half of the game's tracks.
 * Sharp-eared players will notice that in the SNES port of Sim City, the theme for each city size is in fact a heavily-arranged version of the same melody.
 * Descent 3 has an eight note riff recurring throughout most of its soundtrack.

Sports Game

 * Punch Out!! Wii is an interesting example, as each enemy fighter has a remixed version of the classic NES theme, remixed to fit their nationality or personality, for instance:
 * Glass Joe has light hearted french-sounding music.
 * Von Kaiser has dramatic militaristic music. (with Richard Wagner's Ride of the Valkyries for the first tunes!)
 * Disco Kid has... well, I'll let you figure that one out.
 * King Hippo has tropical sounding music.
 * Piston Honda has oriental music.
 * Bear Hugger has fast paced banjo and harmonica music.
 * Great Tiger has Indian mystical sounding music.
 * Don Flamenco has Spanish music. Note the castanets in the backround.
 * Aran Ryan has a jaunty Irish jig.
 * Soda Popinski has a dramatic cossack choir.
 * Bald Bull has some distinctly Turkish sounding music.
 * Super Macho Man has Surfer music.
 * Mr Sandman has a Heavy Metal version.
 * And finally, Donkey Kong has, well, Donkey Kong-esque music.

Survival Horror

 * The Resident Evil series: A recurring riff can be heard in many of the BGMs in Resident Evil 2, including the beginning scene on the street and the musics played while fighting William's many mutations(would that be a Leitmotif instead?). Also, the Extreme Battle Mode musics in the Dual Shock Edition are further variations of this theme.
 * The original version of RE1 has the mansion theme, which occurs in different variations on the first and second floors, and gets remixed into even scarier form when you come back to the mansion from the guest house, which is major Nightmare Fuel, especially when fighting the Hunters and spiders.
 * In Silent Hill 2, the music piece "White Noiz" heard at the beginning of the game reappears in several variations later in the game, for example "The Day of Night", "Heaven's Night", and "Prisonic Fairytale"(played immediately afterward, when Mary's letter is read).
 * That motif also seems to recur in "A Stray Child" from SH3, which also has the "witch doctor" vocal sample heard in SH2 and SH4.
 * The "Theme Of Laura" and "Promise" motifs recur throughout the game. EG, the cutscene music when James reminisces about Mary on the overlook is a variation of Promise.
 * In the hospital after Maria's death, a piano hook from "Forest"(the graveyard cutscene music) is reused, in Tear Jerker fashion.
 * In Clock Tower, the notes that you hear in the track "Satanic Place of Worship" are repeated throughout many songs. It's played for Nightmare Fuel, as with many things in the game.

Third Person Shooter

 * In Syphon Filter 2, the musics in Rocky Mountains, Interstate 70, and Slums District use a recurring theme, as do Mackenzie Airbase and I-70 Bridge, and the guitar motif from the opening cutscene is repeated in Union Pacific Train 101, Club 32, and Slums District Action.
 * The boss themes in the first game were mostly based on the same riff. Also, the Subway, Pharcom Expo, and Missile Silo danger themes use a recurring riff, which also appeared in 2's Prison Escape/Biolab Escape theme.
 * Item Room Ambience has occasionally cropped up in the Metroid series, especially in the older side-scrolling titles. Unfortunately it appears to be out of use as of late.

Turn Based Strategy

 * Final Fantasy Tactics has a reoccurring four-measure riff in nearly every song.
 * Final Fantasy Tactics Advance may be another example. The tune in question is "so, so, so, mi fa so, ^do, (b)ti, (b)la, so" etc..
 * Heroes of Might and Magic V has its main theme recurring everywhere in the game. About 2/3 of the tracks have at least part of the riff of the main theme.

Wide Open Sandbox

 * No More Heroes is positively filled with remixes of its main theme, with variations popping up as in-game battle music, background music in cutscenes and occasionally doing a Theme Tune Cameo when whistled by the protagonist.

Anime and Manga

 * Neon Genesis Evangelion has several recurring themes. "Decisive Battle" in particular is remixed several times, as "Magmadiver" and "Spending Time in Preparation." (Rebuild of Evangelion goes especially wild with this one, with at least five variatons of the main theme.) "Three of Me, One of Someone Else" is a slower and softer version of Ritsuko's theme. "The Beast" reappears as Eva-00's leitmotif, and "The Beast II" as "Normal Blood." And of course, the opening makes a Last Episode Theme Reprise as an instrumental piano piece.
 * Stratos 4 has a number of tracks, including one labeled "Mikaze's Theme" (for the lead main character), that all share a tune. At the last episode, this is revealed to be the tune of the second ending theme (which is used for the ends of whole seasons).
 * Tengen Toppa Gurren Lagann has the song Rap is a Man's Soul (Row Row Fight The Power) appear at various points with wildly varying remixes.
 * The soundtrack for the second season of Spice and Wolf has a number of recurring themes remixed with different combinations of instruments and at slightly different speeds. The most prominent tune is repeated in five separate tracks: Shukusai no Hajimari, Ki no Ii Hitobito, Ookami to Odoru, Nezumi no Shippo Tei, culminating in Matsuri wa Owari, Tabi wa Tsuzuki.
 * Mai Hi ME: The tune in Hime Hoshi (the first track in the first disc in the OST) appears many times, . If you wonder which one, it's the one with One Woman Wail "come ye, come ye".
 * Yuki Kajiura is fond of this trope.

Film

 * The film Give My Regards to Broad Street (a vanity picture for Paul McCartney) uses the verse melody for "No More Lonely Nights" ("I can wait another day") as a Recurring Riff.
 * Dangerous Minds uses the chorus of "Gangsta's Paradise" as a recurring riff.
 * Throughout The Dark Knight, the Joker has a very noticeable Leitmotif - a shiver-inducing electric guitar riff. It appears in five of the songs on the film's soundtrack, each of which plays during a scene in which he features heavily.
 * Sin City has the saxophone in the background of its score repeat in several tracks. So does the singing and modified versions of the bass riff in the opening.
 * Whenever one of the main characters in The Good the Bad And The Ugly does something cool, the background music goes "oo-ee-oo-ee-oo!". The same applies to For a Few Dollars More, except that the sound effect is "DYEEEW".
 * The 2009 Star Trek movie uses the main theme ("Enterprising Young Men") in several places, including part of the credits.
 * Scrooge has "I Like Life" as a recurring theme.

Live-Action TV

 * The bass riff in Seinfeld.

Music

 * Many a Rock Opera. WASP's The Crimson Idol comes to mind in particular. Also notably, Andrew Lloyd Webber and Tim Rice's Jesus Christ Superstar uses the same pieces of music many times throughout the album set to different lyrics.
 * Also, The Downward Spiral by Nine Inch Nails and The Wall by Pink Floyd both feature their own recurring and mutating theme; just a short 4-note pattern in the latter, but eight measures long in NIN's work.
 * The Who's double album Rock Opera Quadrophenia features four "themes", or tunes, found in part of the songs of the album. Listen to the whole album, and those four themes, (each representing a different side of the protagonist Jimmy, who has four personalities) will grow on you.
 * Modest Mussorgsky's piano solo suite Pictures At An Exhibition does this with the "Promenade theme" (which is also non-prominent enough that it counts as a Leitmotif).
 * Dream Theater.
 * Throughout Christopher Tin's Calling All Dawns album, there are several recurring riffs, most notably that of bits of Baba Yetu appearing throughout the album.
 * Each song on Brad Paisley's This Is Country Music ends with a snippet of the title track, themed to the next song on the tracklist.
 * Funker Vogt has used variations of an eight-bar progression in many of their songs.
 * Covenant's "Greater than the Sun", from Skyshaper, has a synth riff nearly identical to "Xrds", the B-side to "Ritual Noise".
 * The Genki Rockets have a recurring theme in "Heavenly Star", "Fly", "Breeze", and probably others.

Theatre

 * This is very popular in modern musicals. Shows like Wicked, Les Misérables and just about anything by Andrew Lloyd Webber have about five tunes reconfigured into twenty songs.
 * Those are usually leitmotifs or dark reprises, though.
 * Wicked has the Overture chord progression, the melody and chords of "No One Mourns the Wicked" and the "unlimited" line from "The Wizard and I" as recurring themes.
 * Les Misérables does this a lot too, especially with "Look Down", which appears whenever something related to prison or misery comes up (Work Song, beginning of The Confrontation, Look Down, in the sewers), and "Fantine's ", which appears in relation to some main characters' deaths. In fact, most of the musical is built on recurring riffs.
 * Running throughout the score of the musical 110 In The Shade is one Ear Worm of a melodic hook. It appears as a fully developed song at the start of first act as "Gonna Be Another Hot Day" and at the start of the second as "Evenin' Star" (though this latter one was a Cut Song for many decades). A shorter Fanfare version turns up at a few highly dramatic moments.
 * The interludes in Benjamin Britten's opera adaptation of The Turn of the Screw are all based on a single theme.
 * Vanities somewhat has this in "I Don't Want To Miss a Thing", "Fly Into The Future", "Let Life Happen", and "Letting Go"(although the last was a Cut Song when the first debuted). Another recurring theme is in "An Organized Life", "Cute Boys with Short Haircuts", and "Friendship Isn't What It Used to Be". The bridge of "Hey There, Beautiful", the chorus of "Feelin' Sunny"(both cut after the 2008 Pasadena production) and the verse of "I Can't Imagine" also have a common theme. The intro of "FITF" uses the melody of the Cut Song "Nothing Like a Friend". The ACT production's version of "Letting Go" reprised part of "Mystery", that show's act opening number.

Western Animation

 * The Batman. Over and over and over again.
 * Avatar: The Last Airbender:
 * loads and loads'' of remixes of the main theme used as background music throughout the series.
 * Not to mention all the versions of the love theme from "The Cave of Two Lovers" whenever things get, um, interesting between Aang and Katara.
 * Sequel Series The Legend of Korra uses several remastered versions of tunes from its predecessor.
 * How to Train Your Dragon features a riff from "Forbidden Friendship" in many different contexts: first played in a minor key when Hiccup, on xylophone as Toothless and Hiccup become friends, as bagpipes and orchestra as they take their first flight together, on strings and xylophone in 3/4 time when Astrid rides Toothless for the first time, and continues to reappear throughout the score.