Dream Match Game

In a Fighting Game, it is a rarity to see two competitors go head-to-head without the use of superhuman skill. These fighters also have the ludicrous ability to recover from even the most fatal of wounds.

However, Reality Ensues. Sometimes, not even being Made of Iron can save characters from kicking the bucket... for good.

In fighters (especially the ones with more longevity), this tends to be problematic for fans. Perhaps the Big Bad was so undeniably cool that he merited a permanent spot on the roster. Maybe that really Badass side character became an overnight hit with the fandom. Or it could simply be that a particular individual was nothing more than pure sex on legs. Either way, their exclusion may prove to be an unwise decision.

To remedy this, many series decide to write the ultimate love letter to their fans by bringing back everyone for one grand battle royale.

Usually, this event will have no bearing on the plotline of the games (expect the next proper installment to disregard this one and pick up from where the preceding iteration left off), but nods to the series' mythos will be dropped frequently. If there is some semblance of a story, it is usually in the form of an Excuse Plot. On occasion (but not too often) it will turn out that this is merely a byproduct of one's dreams or imagination. Nostalgia Levels tend to pop up quite frequently in games like these.

Compare/contrast Ultimate Showdown of Ultimate Destiny (the cross-media version of this trope), Fake Crossover (in that the events of these type of entries will rarely--if ever--be referenced again). Compare Canon Shadow; a character who is there in the game, but not really there in the overall plot.

Not at all related to Match Game, which is a Game Show.

Fighting Games

 * Named for The King of Fighters '98: The Slugfest (more specifically, its Japanese subtitle, The King of Fighters: Dream Match Never Ends). The fifth title in a series that up until 2003 had a new game released each year, this KOF was touted as a "special edition" of sorts. The game did not feature a storyline that year, as the Orochi Saga ended the previous year (for the record, the number of causalities had amounted to 8 by this time). Instead, SNK took the time to include (nearly) every character from the previous games, notably SNK Boss par excellence (Omega) Rugal Bernstein (who died via Superpower Meltdown back in  ' 95), the Oyaji Team (Heidern, Takuma Sakazaki, and Saisyu Kusanagi, who all also last made a playable appearance in  ' 95), Mature and Vice (Iori Yagami's teammates from  ' 96 who he accidentally killed at the end of the game), the New Faces/Orochi Team (who died resurrecting Orochi the previous year), and the American Sports Team, who hadn't been seen since their  ' 94 debut. With its well-balanced, refined gameplay, many video game publications are quick to note this edition as the best entry in the series. To this day, '98 is still fairly popular in Tournament Play.
 * Additionally, it should be noted that Wild Mass Guessing pegs this game as a results of Shingo Yabuki's notes on every fighter he's ever encountered or heard stories of.
 * Its Updated Rerelease,  ' 98: Ultimate Match, took things a step further. Not only did UM include all of the characters from the original game, but it added in the few characters left out: Goentiz and Orochi (respectively the bosses of  ' 96 and  ' 97), Eiji Kisaragi from  ' 95, Kasumi Todoh from  ' 96, the entire  ' 96 Boss Team (most of all, Geese Howard! Alongside him were Wolfgang Krauser and Mr. Big.), Orochi Iori and Orochi Leona, as well as various EX versions of pre-existing characters. While not as critically favorable as its original version (since it is just  ' 98 with a shiny new paint job), Ultimate Match is still seen as a very technical, very fun game to play.
 * The King of Fighters 2002 discarded the "Striker" system found in the previous three games, returning to its roots as a 3-on-3, "last man standing" affair. In addition, its gameplay mechanics were revamped to more closely resemble  ' 98. While many of the characters found in-game came from the current arc, older characters such as the New Faces Team,  ' 97 Special Team (an Odd Friendship trio consisting of Billy Kane, "Blue" Mary Ryan, and Ryuji Yamazaki), Mature, and Vice made a reappearance. Omega Rugal (now voiced by Norio Wakamoto!) even reared his ugly face as the Final Boss. The home ports added Shingo, King, Geese, Goenitz, and Orochi Iori (the latter three only present on the PlayStation 2 and Xbox ports and being taken from the technically earlier-released SNK vs. Capcom SVC Chaos). Although a snazzy tagline ("Be the fighter!") and retooled gameplay didn't earn 2002 the same praise as  ' 98, it does have its fair share of supporters and is seen as one of the series' more notable entries. Not bad considering this was released during the interim that SNK had to pair up with Aruze/Eolith due to their bankruptcy.
 * The King of Fighters: Neowave was essentially a reworked version of 2002 with a few changes. The most significant would be the addition of Art of Fighting 2-era Geese Howard as the Final Boss, a decision that came out of left field for many. This game also added Jhun Hoon and Saisyu Kusanagi, complete with new HSDM/MAX2 attacks for them.
 * And then its proper Updated Rerelease, 2002: Unlimited Match, decided to go for the gusto. If a character was fully playable (this even includes the alternate movesets of certain fighters) in '99, 2000, or 2001, but missed the cut for the original 2002, you can bet your ass that they made it in for this game. Also, Tetsuo Captain Ersatz K9999 was replaced by Nameless, a more balanced character with a tragic backstory who has been better received by the fans than his predecessor. The end result? A whopping total of 66 playable characters, quite possibly the largest in 2D Fighting Game history.
 * While The King of Fighters XII is called a Dream Match, this is In Name Only. The roster was scaled back to 20 characters (with 2 additional characters in the home version), many of them comprising the cast of earlier iterations of the series. The game was admittedly lacking terms of replayability, although it was blatantly clear that it was stomping grounds for XIII.
 * Fatal Fury Special and the later entries of the Real Bout subseries (Special and 2; the first Real Bout was actually canon, culminating with the death of Geese Howard) brought back the majority of the series' cast. Special also included Ryo Sakazaki as a Bonus Boss, which jumpstarted the idea for the Massive Multiplayer Crossover that was the aforementioned KOF. Real Bout Special, in particular, was infamous for introducing gamers to Nightmare Geese, a nightmare of both the literal and figurative variety. The next (and currently final) title (Wild Ambition notwithstanding), Garou: Mark of the Wolves, picks up 10 years after RBFF.
 * SNK seems to love these kind of games. Samurai Shodown V Special offers little in the way of a storyline, instead focusing on gameplay. The 28-man roster was heavily composed of series' regulars.
 * In the same vein, Samurai Shodown VI. All of the cast of V Special returned, as well as seven characters from the first two games that didn't reappear in later incarnations of the series (Genan Shiranui, Cham Cham, Earthquake, Nicotine Caffeine, Neinhalt Sieger, Wan-fu, and Kuroko) and four new fighters (most notably the Ninja Maid Iroha, who became very popular despite only being a one-shot character). The game is set in an unknown year in a parallel timeline based upon the previous entries, and the game's producer even called it a "festival game". The title also introduced a gameplay mechanic called the "spirit select" system, which allowed players to choose between six different fighting styles based on all previous installments similar to the Grooves from Capcom vs. SNK 2.
 * Tekken Tag Tournament, a game made during the transition from Tekken 3 to Tekken 4, boasted 39 characters (the highest in the series before the release of Tekken 6), many of whom were missing from the third game. Kazuya Mishima, the most heavily promoted character of the game, was highly popular with the fans despite his absence after 2; this status allowed the story to work around his presumed death and have Kaz make a triumphant return in Tekken 4. As more of a compilation of the last three games, TTT was non-canon (although there is the case of Unknown, thought to be a demon-possessed Jun Kazama ) and noted for its fun factor (new moves were added to every character, you could mix and match several of your faves, and Tekken Bowl Mode was a blast). If you ask fans of the series if they'd like to see a Tekken Tag Tournament 2, you'd get a resounding yes.
 * Looks like their prayers have been answered. Holy...
 * In a case of What Could Have Been, TTT was originally supposed to be a true sequel to Tekken 3, before being changed in development.
 * TTT2 seems to be playing this trope straight with what would appear to be a pre-Tekken version of Heihachi. Full head of hair and everything!
 * Some info dump: apparently Heihachi has spent the past few years developing a youth elixir of sorts to rejuvenate the body and increase longevity. When it's complete, he immediately uses the drug on himself, resulting in his de-aged appearance (this may overlap with Real Life Writes the Plot, as Daisuke Gouri, the seiyuu of Heihachi since 3, committed suicide in early 2010; the young Heihachi will be voiced by Unsho Ishizuka). Oh, and remember a certain someone named Jun Kazama? Yeah, she's back.
 * In a very strict sense, there's Vampire Hunter 2 and Vampire Savior 2, upgraded/alternate versions of the second and third Darkstalkers games that had little more than aesthetic changes to the roster, the more definitive versions including everyone. However, Vampire Savior's port to PlayStation 2 as part of Vampire: Darkstalkers Collection introduced Dee, Donovan's Super-Powered Evil Side (as evidenced by his Downer Ending in the second game) which looks like Donovan's head placed on Demitri's body. His story (where he encounters an older version of Anita, the very girl he lost himself to darkness to protect) brings up the theory that there's some sort of timeline split after Night Warriors: Darkstalkers II.
 * More or less, Mortal Kombat Trilogy. It follows the same basic story of (Ultimate) MK3, but contains all of the characters present in the previous games. You can even pick retro versions of Raiden, Kano, Jax, and Kung Lao.
 * Another rare canonical example would come from Armageddon, with 61 of the 63 characters hailing from previous games. The Wii version also features Khameleon from the Nintendo 64 version of Mortal Kombat Trilogy, back by popular demand. The reason for Armageddon's canonicity is that it was supposed to Torch the Franchise and Run with a "new generation" cast for the next game, but this idea fell through by virtue of Midway going belly-up. Mortal Kombat 9 does start with nearly everyone dead at the end of Armageddon... only for a dying Raiden to push the Continuity Reboot button in an attempt to prevent Armageddon, thus The End of the World as We Know It, from even happening.
 * On that note, as a reboot visiting altered versions of the first three games, MK9 qualifies as a canonical example, as its roster is basically Trilogy minus "Cyber" Smoke, Rain, and the bosses plus Quan Chi and Cyber Sub-Zero, with Rain brought back later as Downloadable Content.
 * A non-standard example: Onimusha Blade Warriors, which consists of characters from the first three games (plus Guest Fighters Zero and MegaMan.exe) duking it out. The game is set months after the second game, and 11 years before 3.
 * Dissidia Final Fantasy can be boiled down into a simple formula: bring back all the dead-but-awesome bad guys and all the main characters, give some kind of plot about them all being pulled from their respective universes by either an evil god or a not-so-evil goddess, and make a fighting game.
 * Castlevania Judgment does this for the Castlevania series, where newcomer Aeon brings several heroes (|Simon Belmont, Trevor Belmont, Grant Danasty, Sypha Belnades, Alucard, Maria Renard, Eric Lecarde, Cornell, and Shanoa) and even a few villains (|Dracula, Death, Carmilla, and Golem) into the Time Rift so he can unite them in an attempt to stop an usurping by Galamoth (of Kid Dracula and SotN fame). It's unknown exactly how much leverage Judgment has on the rest of the series; several characters have been pulled from times before, during, or after their quests, and many endings hint at plot points introduced in later games.
 * Hyper Street Fighter II: The Anniversary Edition was a 15th anniversary revision of Street Fighter II that was released for the arcades and PlayStation 2 in 2003 (almost a decade after Super Street Fighter II Turbo). It allowed players to use the character roster from any of the five previous Street Fighter II installments (World Warrior, Champion Edition, Hyper Fighting, New Challengers and Super Turbo) and duke it out.
 * The Street Fighter Alpha Anthology had a similar unlockable game called Hyper Street Fighter Alpha. This is a much purer example, as by the time Alpha 3 hit home consoles, the series featured the entire roster from Super Street Fighter II Turbo, along with all the other characters from previous Alpha installments (both, original and from previous games). Some of the characters from the 1987 original were still missing, along with all the new guys from Street Fighter III and all the original characters from the EX series.
 * MUGEN, naturally.
 * Marvel vs. Capcom 2 featured not only the entire roster from the original Marvel vs. Capcom, but also in nearly everyone from every previous Marvel-licensed fighting game by Capcom (X-Men: Children of the Atom, Marvel Super Heroes, X-Men vs. Street Fighter and Marvel Super Heroes vs. Street Fighter) along with many additional characters (including a few originals) for a 56-man roster.
 * Kamen Rider Climax Heroes OOO sort of qualifies, as its main draw besides the inclusion of Kamen Rider OOO (while retaining everone from the past two games) is the addition of absolutely everyone from Kamen Rider Ryuki, pulled straight from the game of Ryuki's American adaptation Kamen Rider Dragon Knight, which ran on the Climax Heroes engine and released on the same year as the preceeding Climax Heroes game... in America only.
 * Naruto Shippuden Ultimate Ninja Storm Generations: Along with the "young" version of certain characters being present, there are plenty of playable characters in the game who have already been killed off in the Naruto manga/anime. The most prominent examples are probably Zabuza and Haku, as several advertisements for the game have made note of their presence.

Other Video Games

 * Warriors Orochi, Koei's Massive Multiplayer Crossover between Dynasty Warriors and Samurai Warriors. Yes, there is a plot, but it is really nothing more than a means to bring together a greater portion of both series' stables, despite the fact that (historically speaking) they exist about A MILLENNIUM APART.
 * Similarly, Dynasty Warriors: Gundam does this with all the different Gundam franchises.
 * Castlevania: Harmony of Despair is this trope applied to the series' usual Metroidvania shtick. The playable characters are Alucard, Soma Cruz, Jonathan Morris, Charlotte Aulin, and Shanoa, with DLC in the form of Julius Belmont, Yoko Belnades, Richter Belmont, Maria Renard, 8-bit Simon Belmont, and Getsu Fuma (from Getsu Fuma Den; think "Castlevania in Medieval Japan"). In other words, you have characters from 1476, 1691, 1792, the early 1800s, 1944, 2035/2036, as well as Alucard (effectively immortal, but theorized to have been born in the 13th, 14th, or early 15th century) all interacting with one another. Bizarrely Justified Trope in that the events of the game take place within a cursed book called the Grimoire, where both Castlevania and the various heroes across time have come to life.