Multi-Mook Melee

Multi Mook Melee is when, instead of or in addition to a Boss Rush, the player may fight a seemingly endless stream of Mooks, Blue Mooks, Cave Mooks, Elite Mooks, Giant Mooks, Metal Mooks, Fire Mooks, Ice Mooks, Light Mooks, Minibosses and the like, which slowly become tougher. This may be featured in the plot (almost any game with an arena is bound to have this) or as a minigame, bonus feature or multiplayer mode.

Generally come in two flavors:
 * 1) Constant stream variety, which takes place in a single room with no rest in between the waves of mooks. In fact, when one mook is defeated, a replacement may immediately take its place.
 * 2) Multi room variety, where the player enters a room, battles a set number of mooks, and then moves on to the next one. Some Multi Mook Melee of this variety give the player a chance to catch their breath before the next group of mooks.

When Multi Mook Melee is turned Up to Eleven, you have The War Sequence, which has you fighting virtually hundreds of mooks at once. When you're surrounded on all sides, expect to Hold the Line and do some Radial Ass-Kicking.

And, of course, you have the ever-popular hybrid of 3M and Strategy: Tower Defense.

Action Adventure

 * The Legend of Zelda The Wind Waker has the Savage Labyrinth, while Twilight Princess has the Cave of Ordeals. Spirit Tracks has the Take 'Em All On minigame, which is a combination of this and a Boss Rush.
 * Wind Waker (and to a lesser extent Twilight Princess) has about a dozen hidden underground rooms throughout the world which drop you into a room flooding with mooks. Darknuts, Moblins, Wizzrobes, and countless hordes of lesser mooks relentlessly attacking one kid, and he cuts them all down with ridiculous arrow sniping and acrobatic sword moves while they all simultaneously attack and defend... needless to say, these moments are some of the highlights of the game.
 * And from the same game, there's the castle full of Mook hordes that get unfrozen the moment you acquire the Master Sword. But what better way to try it out?
 * Many of the post-Symphony of the Night Castlevania games have optional Multi Mook Melee areas. Circle of the Moon has the Battle Arena, a multiple-room area where you are drained of your MP and thus not allowed to use DSS cards. There are several floors of monsters to fight through, but between floors there's a one-way path to leave the area prematurely. Dawn of Sorrow has a mode where you can place monsters in a series of rooms, as long as you have at least one of that monster's soul. However, each monster has a point value assigned to it, and no more than 8 points' worth of monsters can be in a single room. Portrait of Ruin combines the Boss Rush and Multi Mook Melee in its Boss Rush mode, with boss rooms separated by passages with normal enemies. There's also a specific area, the Nest of Evil, which is basically an extremely long Multi Mook Melee with sets of rooms, and one of the bosses from Dawn of Sorrow at the end of each set. After each set of rooms is a teleporter, so you don't have to do the entire Nest of Evil at once. Order of Ecclesia has a similar unlockable area, the Large Cave.
 * The dark realm in Onimusha is essentially this, with you fighting 20 waves of harder and harder enemies in the first game, and up to 100 in the fourth.
 * Metroid: Other M has a hallway just before the control bridge (Phantoon boss arena), where you face some of the more powerful foes of the game. Fortunately, it should mostly be a laugh, as about half of them can be killed with a single Screw Attack, and the rest with a Power Bomb.
 * One of the bosses for the very-poorly-known game for the Game Boy Advance - The Hobbit - is a heart on a wall which you can't reach and have to repeatedly shoot. It's made much more difficult by the fact that unless you occasionally take some time out to kill the HORDE of animate vines which try to kill you, you will die. Particularly considering they can spawn in the way of your shots. Which, if you're using the targetted long-range explosive ones, is a bad thing.
 * One battle in Ys IV, at least the SFC version, had you face off against a legion of Romun soldiers on a small platform.
 * Okami has the Demon Gate Trials -- three optional areas where the player must defeat ten waves of enemies, without much time to rest or heal in between. Brutal? Yes, but if you want Hundred-Percent Completion...

Action Game

 * The Matrix: Path of Neo contains several. Early ones are training exercises for battling multiple opponents, which is useful later on when it's Neo versus hundreds of Smiths at a time.
 * Several areas in God of War, but especially the second phase of the Ares boss battle, wherein Kratos has to defend his family from a very long stream of... himselfs. If they manage to kill your family, well... Have a Nice Death.
 * Ninja Gaiden gives you the joy of the 60 fiend challenge which is exactly what it sounds like.
 * And in hard mode it becomes 80 fiend challenges. In very hard, 100. In Master Ninja, 120. Ninja Gaiden 2 on Xbox360 has the tests of valor which are the same principle except you're teleported in a closed arena with no escape (these were removed in Sigma 2 though).
 * Batman: Arkham Asylum: The corridor leading to the final boss contains 20 really tough Mooks, all of whom are applauding you on Joker's orders and / or anticipation of the upcoming fight. None of them will attack you unless you throw the first punch. Due to the cramped space, it takes endurance and a lot of patience to survive. It can be helped a little by spraying the floor with Explosive Gel first though.
 * There's a more traditional version of this at one point in the game, where elevators keep delivering waves of mooks. Given the fighting system in the game, it can either be That One Boss, or a personal Crowning Moment of Awesome.
 * There's also a challenge map that provides a literally endless supply of mooks to fight.

Beat Em Up

 * Castle Crashers is all about this when you're not fighting a boss.
 * Hell, even when you ARE fighting a boss. The very first one has a mook come out of the gathered crowd when the boss has half HP (killing him only draws out another) and when the boss has 1/4 HP, you get two to deal with.
 * Many Beat'Em Up games have at least one room (if not the entire game) like this.
 * Kirby Super Star, being some kind of game Anthology, has a few miniboss fights consisting of waves of Elite Mooks. There is also The Arena, which has a Boss Rush mixed with Multi Mook Melee.
 * The DS Remake adds 2 more arenas to the mix.
 * The final areas of most Double Dragon games, which mix this with Boss Rush.

Fighting Game

 * The Trope Namer is Super Smash Bros., which has the "Multi Man Melee" and "Multi Man Brawl." Several variations also exist, the worst being the "Cruel Melee," in which you face massively overpowered enemies without any items, and defeating even one foe is considered an achievement.
 * Brawl steps it up by requiring players to knock out 5 and 10 mooks in a single session of Cruel Brawl in order to unlock two things.
 * Melee also features a trophy for knocking out 5 mooks in a single Cruel Melee session. And then there was that one April Fool's joke...
 * The battle against The Dragon and the Final Boss of Magical Battle Arena begins with you taking down waves of Gadget Drones until you've taken down enough of them for the boss to come out.
 * Some MUGEN creators have gotten rather creative and have made some of these to be used as boss fights. The X-Men: Second Coming game has two of them.

First- / Third-Person Shooters

 * * Gears of War 2's "Horde Mode" re-codified the trope for modern shooters by being one of the first wide-release games to feature waves of enemies that actually shot back, directly inspiring the similar modes that have since been added to Halo and Modern Warfare, among others. It's still common to hear any other game's wave-based mode called "Horde" in casual conversation. Gears 3 added some Tower Defense elements, but kept the basic concept.
 * The last level of Serious Sam - The Second Encounter does this right before the final boss fight and brings it to epic proportions, complete with the sky becoming dark and meteorites raining down during the battle as you wait for the waves to end and the door to the boss area to open.
 * Twice in Serious Sam - The First Encounter and once in the Second Encounter, even the bar appears when fighting group of enemies to show how much there's left.
 * This is more than just twice. There are many sequences (at least on Hard/Serious difficulty where there a large number of targets but do not have boss bars, and they can easily consume your whole pack of ammunition if it weren't for ammo pickups, and even then, it still takes a lot of ammo. Also, the whole point of the game was flinging large quantities of mooks against you.
 * Marathon Infinity with its penultimate level "You Think You're Big Time? You're Gonna Die Big Time!". Those grey pfhor hunters are mean.
 * Which is quite mild, compared to the Secret vidmaster version of it. It has the grey versions mentioned above AND tons and tons of normal pfhor soldiers.
 * Halo 2: The battle in the Mausoleum (aka the "Breaking Benjamin room") on the Gravemind mission. Seems to be the series' homage to Marathon's "You Think You're Big Time" level. Mainly Elite Mooks and and Giant Mooks, including Brutes, Ultra Elites(including stealth-camouflaged ones), Spec-ops Elites, the "Honor Guard Councilor" glitched Elite(supposed to be a Gold Elite), Hunters, etc.
 * Later, Bungie realized they could follow Gears of War and synthesize this trope into Firefight mode. In ODST and Reach, depending on the map, you can face just about everything the Covenant can throw at you: Grunts, Jackals, Jackal Snipers, Skirmishers (Reach), seven varieties of Elites (Reach), Brutes, Hunters, those bug things (ODST), Engineers, ghosts, and even Wraith tanks.
 * Many custom "slaughter maps" for Doom are essentially series of ever-harder Multi Mook Melees. Some fights in the map "Deus Vult" involve over 200 monsters at a time.
 * In Left 4 Dead, It is almost inevitable that at some point your team will become overwhelmed by hordes of zombies stemming from nowhere, forcing you to resort to melee attacks.
 * Call of Duty World at War has the Nazi Zombies mode, which has four characters battle unlimited hordes of zombies (and in some cases, HellHounds) in waves on the four maps, with the enemies taking more and more hits to kill and only short breaks between waves.
 * Every Call of Duty game is largely based around a series of encounters in which the player must advance through the level in the face of endlessly spawning mooks. When the player reaches a checkpoint, the mooks stop spawning.
 * Spec-ops survival mode in Modern Warfare 3 is this. A helicopter, three Juggernauts, and several dozen mooks becomes normal fare at higher levels.
 * The final level of Pathways into Darkness has you fight through one room after another filled with each type of enemy you've encountered.
 * Quake combines this with an Elevator Action Sequence at the end of Episode 2, featuring a Shambler or two, depending on the difficulty), several Fiends and Zombies, and a pair of Vores. Quake IV has you fight a trio of Tanks, then Hovertanks, then Stream Protectors, before the Final Boss.
 * The Proving Grounds in Descent 3 have you fight through four arenas full of mooks, each concluding with an upgraded version of the Stinger, Thresher, Sixgun, and Tailbot, respectively, as minibosses.
 * The Totem defense sequences in Turok 2 combine this with a Protection Mission.

MMORP Gs

 * Aion: the Tower Of Eternity. Also, the Tower Of Evermore.
 * The "Friends?" battle quest in Vindictus has as the main boss fight a pitched battle against 100 Veteran Gnolls, the toughest mobs on the first boat, in addition to a good number of Gnoll Archers, in roughly six or so waves. If you should survive the whole thing, you then have to fight the actual boss, the Veteran Centurial Captain of the gnolls.

Platform Game

 * Combat in Prince of Persia: Sands of Time seemed entirely based on the 'kill one mook, another takes its place' variant. Technically enemies come in waves, but you only notice this on the rare occasions when the game gives you a few seconds to rest between waves.
 * The first two games in the Legend of Spyro trilogy are absolute chock full of these.
 * Sonic Heroes has Robot Carnival and Robot Storm, where the melee is the boss. Robot Carnival (the first one) takes place on one platform, but in Robot Storm, you have to go between platforms after defeating certain numbers of waves (except for Team Rose, which has only one platform). Also, in Robot Storm, the enemies are tougher.
 * The Mini-Boss Tower in Kirby's Adventure, and the third level of Ripple Star in Kirby 64.
 * Bionic Commando had this during many of the Reactor Boss fights.

Role Playing Game

 * Both Kingdom Hearts games had this in the Olympus Coliseum.
 * A more straight example can be found in the End of the World right before the final save-point in the game you have to defeat enemies that steadily increase in danger climaxing in the horrible situation of 8 Angel Stars and 8 Invisibles.
 * Paper Mario: The Thousand-Year Door has the Pit of 100 Trials. Super Paper Mario has two.
 * Super Paper Mario also has the Sammer Guys, 100 characters that need to be defeated one after another.
 * Several of the Missions in Final Fantasy VII: Crisis Core and...
 * The bonus dungeons of the the Final Fantasy Advance series seem fond of this trope. Yang's Trial in Final Fantasy IV Advance is based on this trope, as is the entire Soul Shrine in Final fantasy VI Advance.
 * In Baldur's Gate the Watcher's Keep dungeon has a room like this. However, what it spawns are orcs, so you can pretty much just set everyone to auto-attack and relax.
 * There's also the first challenge in the Pocket Plane, which has you fighting enemies one after the other, starting with goblins and gradually working your way up to Drow, or their good-aligned counterparts for an evil party.
 * Tales of Vesperia has the 10-man Melee, the 30-man melee, the 50-man melee, the 80-man melee, the 100-Man Melee, and if you defeat the Cameo Bonus Boss at the end of the Bonus Dungeon, you can face the 200-man Melee, which starts with the 100-Man Melee, but you keep going and begin facing various Cameo Bosses, first is Dhaos then it eventually ends with a rematch 1v1 with the Bonus Boss Kratos.
 * If you don't want to fight human opponents, Golden Sun's Battle Arena multiplayer mode has a Monster/Boss Rush-esque Multi Mook Melee, which features everything from weak opponents to much-hated Bonus Boss Dullahan.
 * The Force Unleashed features a big hangar directly at the beginning of the last level with multiple Chicken walkers, Purge/Evo- and Jettroopers and some standard Stormies. You are able to skip this completely by dropping through the floor, but it is interesting to see how far you come with your strenghts and to level up.
 * There is a battle in The Bard's Tale: Tales of the Unknown where you can fight four groups of 99 berserkers each. If you've leveled your characters enough, they can't hit your front-line characters and your sorcerer characters will have a spell that hits all enemies in the battle. Start the battle and go off to get a drink.

Shoot Em Up

 * How's this for an Ur Example? Space Invaders.
 * The indie game Meritous has these in the form of Treasure Rooms. When you enter one, the doors close and the monochrome graphics turn red, as droves of enemies warp into the room in short bursts. After you've killed them all, you get a metric ton of PSI crystals, as well as some treasure chests which may have either a bonus of crystals, a free upgrade to one of your abilities, or one of the upgrade items (which, while not necessary to complete the game, make things much easier).
 * Planetary defense fleets in Escape Velocity. If you've got a good ship, this is primarily a test of patience, since it means fighting 50-1000 enemies 1-5 at a time.
 * In the freeware game Hurrican, the 1st boss of the penultimate level is a massive onslaught of enemies, unlike with the other bosses (where hitting a certain point causes damage), destroying individual enemies causes the boss life meter to go down.
 * ~Rush'n'Attack~ has said melee at the end of the stage; quite dangerous for the One-Hit-Point Wonder equipped with a knife
 * Bio-Hazard Battle has the boss of stage 7... which is nothing but a TON of deceptively weak, floating mechanical-looking objects that tend to crash into the player's ship as well as firing a lot of shots.
 * Alien Shooter and its cousin Zombie Shooter turn this trope to eleven. Late-game levels have hundreds upon hundreds of enemies in every room, and no, it's not an exaggeration for emphasis.
 * Heavy Barrel usually had this during elevator sequences.
 * Commando ended every level with this.

Simulation Game

 * Rogue Squadron III: Rebel Strike features a walkabout level where you have to survive multiple waves of mooks. It's debatable whether this was a good idea in a flying game.

Sports Game

 * The Showdown swordplay event in Wii Sports Resort. The event has the player take down dozens of sword wielding miis. Most of them are KO'd in one hit but some take two and the final enemy (a boss if you will) has to be hit 3 times.
 * The Fielders' Challenge in Backyard Baseball 2005 has elements of this; you have to win against an unlimited number of robots.

Stealth Based Game

 * Metal Gear Solid 4 features a Multi Mook Melee.
 * Metal Gear Solid 2 has the circular chamber in which . It's also home to the infamous Fission Mailed screen.

Survival Horror

 * In Karim's chapter of Eternal Darkness, upon finding the Ancient's essence, he is subjected to a large gauntlet of zombies, and even a couple of Horrors in order to earn the right to approach it. Earlier in the chapter, after acquiring a Ram Dao, a smaller-scale gauntlet must be fought through.

Third Person Shooter

 * The Lupino Showdown from the original Max Payne, which has Max fighting roughly thirteen mooks that swarm in one after another after him before Jack Lupino himself makes his entrance with two of his personal guard and a sawed-off shotgun.
 * In the sequel, after you beat the game once you unlock the "Dead Man Walking" mode, where you can fight an endless stream of enemies spawning constantly in an enclosed area.
 * Wet's arena stages have Rubi blasting up mook after mook while trying to make it to the markers that allow her to disable the doors that they spawn from. Once all the doors are disabled, it's just a matter of mopping up anyone still standing before moving on to the next area.
 * Certain areas of the free-roam section of Global Agenda are this, as are most of the Player Versus Environment missions.
 * Some levels of P.N.03 end with this in place of a Boss Battle, such Mission 4, or accompanying a Reactor Boss, as in Mission 6.

Turn Based Strategy

 * Featured in Crush Crumble and Chomp, where the combined forces of humanity are the "mooks" amassed against you.

Wide Open Sandbox

 * The first Shenmue game has one of these, where you fight 97 Mooks with 3 Minibosses mixed in. It's in the main game, but after you complete it you're allowed to go through it again, at least on the Dreamcast version.
 * This one is especially notable as it was 1.) the largest melee fight on a console at the time, and 2.) ALL of the combatants had a unique model and skin. Needless to say it was a memorable part of this troper's childhood.
 * Not to mention the sheer BadAssedness of protagonist Ryo kicking the shit out of one hundred different people at once.
 * A feature of the Big Bad's headquarters in Scarface the World Is Yours. Fortunately enough mooks zapped and taunted allowed moments of invincibility. Space 'em out, you'll need 'em.
 * The first hunter encounter inside the first military base you enter in Prototype. As you kill your first hunter, then the next two, more and more pour in at once. Subverted in that the number that enter the base each time caps out and they don't become tougher over time.