->''"Look, it's the extra dungeon for after you beat the game. Good luck!"''
-->-- '''Alice Margatroid''', ''[[VideoGame/{{Touhou}} Subterranean Animism]]''

Where the BonusBoss usually lives. As mentioned, hardcore gamers (especially fans of [=RPGs=]) often feel cheated that the popularization of video games has led to a lessening in difficulty.

The BonusDungeon will be bigger, badder, and with more levels than the other stages in the game. It will be filled with new monsters. Sometimes game designers cut corners by making the monsters simple [[PaletteSwap recolors]] of common monsters, but with [[UndergroundMonkey higher stats]].

Sometimes, the InfinityPlusOneSword will be waiting at the bottom.

Compare SecretLevel. Often a BrutalBonusLevel.

Since these are usually secret levels, expect the examples to spoil accordingly.
----
!!Examples:
[[foldercontrol]]

[[folder: Action Adventure Games ]]

* ''Franchise/TheLegendOfZelda'':
** There's an extra dungeon in ''VideoGame/TheLegendOfZeldaALinkToThePast'' in the ported GBA version. Players can't access the dungeon until they completed the multiplayer Four Swords game. Inside the dungeon is 4 areas with very tough puzzles and color swaps of some of the bosses Link fought previously, along with new behavior patterns. Beating all 4 bosses opens the way to fighting 4 clones of Link from the Four Sword, each Link bearing a different color and abilities that mirror Link's. Beating these bosses only gets you statistics of your game data, so it's nothing but bragging rights.
** ''VideoGame/TheLegendOfZeldaLinksAwakening [[UpdatedRerelease DX]]'' has the Color Dungeon, which is only accessible by playing the game on a Game Boy Color. It includes color-based puzzles, such as colored switches and enemies that are only distinguishable by their tunics having to be beat in a certain order. For winning, you get either a Red or Blue Tunic, which puts you permanently under the effect of a Piece of Power (increased speed and attacks send enemies flying and do double damage) or a Guardian Acorn (double defense), respectively.
** ''[[VideoGame/TheLegendOfZeldaOcarinaOfTime Ocarina of Time]]'' has the Gerudo's challenge, out in their outpost, which consists of solving puzzles in different rooms to collect keys. These keys are used in a maze to get the Ice Arrows. While rumors suggested that the cave could be made {{Unwinnable}}, the Fortress is ''always'' solvable.
** ''VideoGame/TheLegendOfZeldaTheWindWaker'' has a number of multi-level gauntlets. Only one is required to finish the game, the rest are hidden on islands around the Great Sea. The (optional) final 20 floors after the required gauntlet form the BonusDungeon.
** ''VideoGame/TheLegendOfZeldaTwilightPrincess'' has the Cave of Ordeals, a gauntlet of monsters similar to the ones in ''The Wind Waker'', with monsters ranging from a single one of the weakest monsters in the game, to three of the strongest and fastest monsters at the same time. If you can reach the bottom, you'll find an inexhaustible supply of a potion that fills your health gauge and temporarily boosts your offensive capabilities, making you unstoppable in combat. Although if you ''can'' reach the bottom, you likely won't need that kind of advantage, even against the final boss. You can go back to it afterwards and find the [[UpToEleven the difficulty has increased]].
** Also in ''Twilight Princess'', lantern caves. They are huge complexes of tunnels that require your lantern to light the way while you fight your way past monsters and pitfalls, collecting an assortment of goodies on the way.
** The two ''[[VideoGame/TheLegendOfZeldaOracleGames Oracle]]'' games for GBC also includes special dungeons, available only in linked games. They can be found wherever you get the sword in an unlinked game--you start the game with the sword, so you never have to go there.
* ''VideoGame/{{Okami}}'' features a particularly evil example. In different areas of the overworld there are 3 caves that are home to (slightly) upgraded versions of a previous giant demon spider boss. Defeating them earns a reward, but you can then return to the same cave later to find a demon gate eerily sitting there. Going through forces you to battle wave after wave of superpowered regular enemies. Even the lowliest of {{Mooks}} can waste you with a couple of hits in these battles (oh yeah, you have to go through 10 of them to get the reward) and have HP that would make some of the late-game bosses jealous. These battles could be considered a refreshing change of pace compared to the general easiness of ''Okami'' if not for their sheer sadism. The most difficult cave has you face several bosses from the past in groups, usually two or three at a time. Including [[spoiler:Waka and two possessed Raos]], no less.
* ''TheTowerOfDruaga'', in the ''Namco Museum Vol. 3'' CompilationRelease on the Playstation, had two secretly unlockable 60-floor towers both harder than the original: "Another Tower" and "Darkness Tower", the latter having many new treasures. The Famicom and GameBoy versions had a different "Another Tower."

[[/folder]]

[[folder: First-Person Shooter ]]

* ''Doom 2'' from the ''VideoGame/{{Doom}}'' series had 2 bonus levels "Wolfenstein" and "Grosse" that were {{Shout Out}}s to the game ''VideoGame/Wolfenstein3D''
* ''VideoGame/{{Marathon}} Infinity'' has the [[SeriousBusiness vidmaster]] levels. These levels are accessed through a secret area on the last level, and basically put you in three of the hardest levels of the series (One from each game), pitted against the hardest form of each enemy. The reward: Bragging rights.
* The first two ''{{Descent}}'' games had several secret levels, where the difficulty jumps from the regular levels' NintendoHard to ''VideoGame/NinjaGaiden'' levels. Level 30 (secret level 3) of ''Descent'' on Insane difficulty is nearly impossible to beat. There's also the second secret level, where to rescue the hostages and get HundredPercentCompletion, you have to shoot the doors from the inside while being assaulted by endless waves of {{Invisibility Cloak}}ed Hulks and Drillers.
* ''MedalOfHonor Underground'' featured a campaign after the main game. Players reprised the role of Jimmy Patterson, hero of the first game, as he stormed the castle of a [[StupidJetpackHitler mad Nazi scientist]]. The castle was replete with...interesting...new enemy types, including attack dogs operating armored vehicles and automatons made from suits of medieval armor. Patterson even constructs his own automaton - a man-sized nutcracker.
* EYEDivineCybermancy has cm_cu_minos, which until the recent patch was the only included "custom" mission. A large and semi-mazelike map whose floor is full of holes, forcing you to take it slowly and carefully. The practically constant monster spawns ensure that even restocking ammo can be a challenge. The missions range from the innocuous (destroy a few harmless beacons or kill x regular monsters) to the outright cruel (slay the Master-rank Deus Ex, which easily soaks more than ten shots from a gun that three-shots its lesser brethren). And it's always full of Kraakanaguls, the big guys that dual-wield warhammers. Sometimes one of your missions is to kill all of them. Your reward? Whatever EXP and money you got from doing the mission, plus a little extra cash on top.

[[/folder]]

[[folder: Hack and Slash ]]

* The PlayStation translation of ''[[VideoGame/{{Gauntlet}} Gauntlet Legends]]'' had several of these, including one-level versions of every stage that got cut from the PS1 version. However, after all the [[BonusDungeon bonus dungeons]] composed of stages cut from the arcade version, the game had as its final hidden stage... [[EasterEgg the building the developers made the game in]]. The sole enemy? A giant hamster, the development team's "mascot."

[[/folder]]

[[folder: Platform Games ]]

* ''Franchise/{{Castlevania}}'' has had several Bonus Dungeons over the course of the series.
** The Towers of Eternity and Evermore in ''VideoGame/CastlevaniaCurseOfDarkness'' - both are fifty floors and feature large amounts of combat, and the latter can only be accessed from the former.
** The Nest of Evil in ''VideoGame/CastlevaniaPortraitOfRuin.'' Could only be accessed after exploring 888% (Yes, 888%) of the castle. Mostly just previously fought enemies, with bosses ripped right out of previous games. No real story, though getting to the bottom will net you the most powerful double-team spell in the game.
** The Battle Arena in ''VideoGame/CastlevaniaCircleOfTheMoon.'' Very challenging in that your Magic Meter is drained while inside. (Though a trick can let you cast one spell if you're quick) You can bail out if it proves too tough, but you have to play it completely through in order to get one of the most powerful suits of armour in the game.
** The Forbidden Area in ''VideoGame/CastlevaniaAriaOfSorrow''. It's home to a somewhat good weapon, a powerful piece of armor, and the [[InfinityPlusOneSword Claimh Solais]], which on top of having a very high Attack stat is remarkably long and swings in an arc, attacking enemies above and ahead.
** The Floating Catacombs in ''VideoGame/CastlevaniaSymphonyOfTheNight''. It's home to [[BonusBoss Galamoth]], [[ThatOneBoss the most powerful non-Dracula boss in the game]]; defeating him nets you the Gas Cloud relic, which makes your mist form harm enemies. The Floating Catacombs are completely optional, since there are no Vlad relics up there.
** In a way, the Stage 5' in ''VideoGame/CastlevaniaRondoOfBlood''/''Dracula X Chronicles''. Accessing it in ''Rondo'' requires that you beat the game, and accessing it in ''[=DXC=]'' requires that you defeat Death, the boss of Stage 5. Until you do so, if you try to get a blue orb (which takes you to lower-path stages) in Stage 4 or 4', Death will change it to red. Oh, and if you think the rest of the game is hard, [[NintendoHard Stage 5' kicks the difficulty up a few notches]].
** The Training Hall and the Large Cavern in ''VideoGame/CastlevaniaOrderOfEcclesia''. While the latter is a MonsterArena, the former is strictly a platforming challenge.
* Every game in the ''VideoGame/{{Klonoa}}'' series includes one or more "EX Visions" available after completing the main plot. These are usually much harder than anything else in the game.
* ''VideoGame/{{Eversion}}'' has Stage 8 [[spoiler:and '''[[LayeredWorld Layer 8]]''']], which is unlocked by getting all the gems before finishing Stage 7.
* ''Franchise/SuperMarioBros'':
** The Trial Galaxies in ''SuperMarioGalaxy'' are unlocked by finding all three Green Stars. The galaxies in the Garden, meanwhile, are unlocked when all Grand Stars minus that of the final level are collected.
** ''VideoGame/SuperMarioGalaxy2'' has the Grandmaster Galaxy after completing everything else, found in World S (itself a post-finale BonusStage).
** The series's UrExample is Worlds 9 through D in ''VideoGame/SuperMarioBrosTheLostLevels.'' They're unlocked after completing the first eight worlds without using cross-world warp pipes (in the NES version, the game has to be completed ''eight times'', but in ''All-Stars'' only once will suffice).
** Star Road and Special World in ''VideoGame/SuperMarioWorld''. The first world is accessed at five different places in the main seven worlds; the second is unlocked via the secret exit in the final level of Star Road (for which it's required to have all colored blocks activated in the game).
** The ''VideoGame/NewSuperMarioBros'' games have one of these in each game unlocked by beating the game, starting with ''VideoGame/NewSuperMarioBrosWii''. That one is based off of Special World from ''World'', ''VideoGame/NewSuperMarioBros2'''s is simple, and ''VideoGame/NewSuperMarioBrosU'' has it based off of Star Road from ''World''. [[spoiler: Like Star Road, there is once again something unlockable in the middle, though it is only one level instead of a whole world this time.]]
** ''VideoGame/SuperMario3DLand'' outshines all of the previous ''Mario'' games in this regard, and currently all of the following. ''Eight'' full special worlds, each one a counterpart to one of the standard worlds full of RemixedLevel[=s=]. [[spoiler:Special 8 has a BrutalBonusLevel on its own, likely a nod to ''Super Mario Galaxy 2''.]] Its sequel, ''VideoGame/SuperMario3DWorld'', has four -- but one of which only has three levels.
* ''VideoGame/DonkeyKongCountry 2'' and ''3'' both have Lost Worlds that you need bonus coins to enter, and these coins are hidden in the regular levels. ''VideoGame/DonkeyKongCountryReturns'' has the Golden Temple, accessible only after completing the Temple levels in the regular worlds.
* ''DistortedTravesty'' has a number of unusually difficult bonus areas that open up along the way. However, the big one is the Spire of Forgotten Souls, a 100 floor TimedMission[[note]]although you get a time reset and full heal every 5 floors[[/note]] filled with some of the most devilish PlatformHell that the creator could come up with. The BonusBoss lurks at Floor 100, as well.

[[/folder]]

[[folder: Puzzle Game ]]

* ''VideoGame/RollAway'' has The Final, 20 levels much larger and more complex than in the main game and you can only save at the half-way mark.

[[/folder]]

[[folder: Role-Playing Games ]]

* The Ancient Cave in the ''{{Lufia}}'' series has gone from 12 levels (''VideoGame/LufiaAndTheFortressOfDoom''), to 100 levels (''VideoGame/LufiaIIRiseOfTheSinistrals''), to 200 (''VideoGame/LufiaTheLegendReturns'') throughout the various games on SNES and Gameboy.
* Very common with ''Franchise/FinalFantasy'' games, especially in {{Updated Rerelease}}s and remakes.
** The Gameboy Advance version of ''VideoGame/FinalFantasyI'' added four unlockable dungeons containing bosses from the 3rd to 6th games in the series. The PSP and iOS versions kept those and added a new dungeon on top of that, called the Labyrinth of Time.
** ''VideoGame/FinalFantasyII'' added the Soul of Rebirth quest for the GBA and the Arcane Labyrinth and Arcane Sanctuary for the PSP/iOS.
** ''VideoGame/FinalFantasyIII'' had one of these ATTACHED to the VeryDefinitelyFinalDungeon, with a TON of BonusBoss characters, each guarding a specific class' InfinityPlusOneSword. Though it is mostly easier than the rest of the dungeon, and the game itself recommends to tackle it. There also several others throughout the game like the Sunken Cave and Bahamut's cave. The 3D remake also adds an optional "???" dungeon, in which the all-new superboss is fought.
** ''VideoGame/FinalFantasyIV Advance'' added two new dungeons, one on Mt. Ordeals, containing new equipment due to the fact this version added the ability to switch party members, and the Lunar Ruins, which contains character specific trials. The DS version removed both dungeons along with the option of party customisation. The Complete Collection for PSP, being based off the GBA port, restored all of it.
** ''VideoGame/FinalFantasyIVTheAfterYears'' has one at the end of each character's individual chapter, usually given by the MoonRabbit Challengingway. Golbez gets ''two.''
** The Sealed Temple in ''VideoGame/FinalFantasyV Advance''. There are a ton of these in the original game as well, such as the water tower in Worus Castle (which gave you the Shiva summon), the basement of Castle Bal (for the Odin summon) and several others. Technically, everything after the Pyramid is optional, as you can go straight to the VeryDefinitelyFinalDungeon as soon as you reclaim the GlobalAirship in the third world.
** Fanatics' Tower in ''VideoGame/FinalFantasyVI'', as well as Ebot's Rock, the Ancient Castle, and many others, all available during the second half of the game. Also the Dragon's Den in ''VideoGame/FinalFantasyVI Advance'', which is much more hardcore than any of those, and has a ''MUCH'' harder BonusBoss. The Soul Shrine, also added in the GBA version, is something of a boss rush mode.
** Shinra Mansion and the Sunken Gelnika in ''Video Game/Final Fantasy VII''.
** The Deep Sea Research Facility in ''VideoGame/FinalFantasyVIII''.
** The Omega Ruins in ''VideoGame/FinalFantasyX''.
** The Via Infinito in ''VideoGame/FinalFantasyX2'' was also 100 levels deep, and tied into the plot, having spirits of enemies (some who only died in {{cutscene}}s and not in fights with the main character) from ''VideoGame/FinalFantasyX ''corrupted into fiends as bosses every 20 levels, finishing off with undead BareFistedMonk Trema.
** ''VideoGame/FinalFantasyXII'' has a TON of these, most of them incorporated into areas explored earlier in the game. Among the most difficult: The side wing of Barheim Passage,the Garamsythe Waterway depths, site 11 of the Lhusu Mines, the top half of the Great Crystal, the Subterra of the Pharos Lighthouse, and Phase 2 of the Henne Mines. There's also the Nabreus Deadlands and Necrohol of Nalbudis. How bad is it? The goddamn [[EverythingTryingToKillYou save/gate crystal tries to kill you.]]
** Deep Dungeon in ''VideoGame/FinalFantasyTactics''.
** ''VideoGame/FinalFantasyTacticsA2'' has the Brightmoon Tor. There are three entrances, and each one has the player go through several consecutive battles before facing level 99 opponents on the top. The tor features monsters that only appear there, with insanely high speed stat and incredibly powerful abilities, such as the ability to cast Haste on all of their units, or reduce a target's HP and MP to < 10.
* [[MightAndMagic Might and Magic: World of Xeen]]:
** After freeing Sandro, the Lich-ruler of Necropolis, you get the key to the game's bonus dungeon, the [[IDontLiketheSoundofThatPlace Dungeon of Death]], which requires access to both Clouds of Xeen and Darkside of Xeen to enter. Upon entering the Dungeon of Death, expecting highly difficult end-game enemies... the level is instead completely devoid of any enemies at all. It is actually a giant crossword puzzle.
** Played straight in the lower levels of Dungeon of Death, once the crossword puzzle has been solved. However, level 4, the final level, is very goofy, full of [[DegradedBoss Xeen-Maker Machines]], and the only actual reward for completing it is a silly and utterly pointless Easter egg.
* ''VideoGame/VagrantStory'' has a bonus dungeon called the Iron Maiden. While areas in the game has a map to show which path leads to where, the Iron Maiden map doesn't. There's minimal to no light in the Iron Maiden, and the enemies are much more menacing than usual, and that's [[NintendoHard saying something]]. The boss waiting at the end is the reason why this dungeon is called "Iron Maiden".
* The Abyss in ''VideoGame/{{Wild ARMs 1}}'', ''[[VideoGame/WildArms3 3]]'', and ''Alter Code F''. It was smaller in the first game, but all later incarnations had it at 100 levels deep. It exists in 5 as well, along with three other {{Bonus Dungeon}}s, but it's much smaller.
* The Chicken Level in ''DungeonSiege''. Hidden behind a series of riddles and item-gathering quests, this was populated with... well, killer chickens with an extraordinary number of hit points. The level was filled with large amounts of fabulous treasure and hard-to-find items for anyone brave and strong enough to defeat the fowl beasts (pun intended).
* The Cow Level in ''Diablo II'' (and the ''Hellfire'' ExpansionPack for ''VideoGame/{{Diablo}}''), inserted as a response to a rumor from the original ''VideoGame/{{Diablo}}'' that such a place existed. Later, the 1.11 patch introduced an elaborate Pandemonium quest with several bonus dungeons.
* The Hades Cup in ''VideoGame/KingdomHearts'', as well as the Paradox Cups in ''VideoGame/KingdomHeartsII''. Also, the ''[[UpdatedRerelease Kingdom Hearts 2 Final Mix]]'' version contains the Cavern Of Remembrance, a bonus level full of very difficult {{Palette Swap}}s of enemies as well as normal enemies with their stats jacked incredibly high--and at the end are no less than thirteen {{Bonus Boss}}es.
* Several examples from the ''VideoGame/{{SaGa}}'' series:
** ''VideoGame/{{SaGa 2}}'' (''Final Fantasy Legend II'' in North America) has the aptly-named Nasty Dungeon with single-tile hallways that span multiple screens and lead to dead ends and monster encounters the party cannot run from. Naturally the strongest weapons and equipment in the game are found here.
** The Netherworld, Auldburg, Trials of Elore, Jewel Beast's Lair, Purgatory, and Shadow Palace in ''VideoGame/{{Romancing SaGa}}''. You only need to visit one of the first 3 that are mentioned in order to progress the story, You can open up all three before starting the endquests, but [[spoiler: after completing Auldburg or The Netherworld, you cannot access the Trials of Elore.]]
** ''VideoGame/{{Romancing SaGa 2}}'' has several: the Ice/Snow/Sand Ruins as well as a hidden town which allowed an deeper explanation of the game's backstory.
* ''VideoGame/PaperMarioTheThousandYearDoor'' contains a bonus level called the Pit of 100 Trials. This gives you a new badge/item every 10 floors, and Bonetail, the BonusBoss, lives at the bottom.
* A similar Pit of 100 Trials is also found in ''VideoGame/SuperPaperMario''. And after beating ''Super Paper Mario'', you can do [[spoiler: all of Chapter 6, and there are no interruptions this time. You need to beat all 100 fighters in a row without leaving. However, unlike the Pit of 100 Trials, you save after every 25 fighters, making it somewhat easier. After defeating End Boss, who is somewhat of a BonusBoss, you get a Bragging Rights Reward: Catch Cards for the partners from the previous game.]]
* The ''{{Pokemon}}'' games have these, starting with Mewtwo's lair, the Cerulean Cave in ''VideoGame/PokemonRedAndBlue''. They are inaccessable until after you've beaten the game, and at the end lies a powerful legendary Pokemon for the player to catch, making it both a BonusBoss and an InfinityPlusOneSword. Generations II and III possess a different variant. After the bonus dungeon you encounter, rather than a high-level Pokémon, a trainer with ''six'' high-level Pokémon, often the highest in the game. In GSC this is [[spoiler:Red, the protagonist of the original games as well as the male choice of protagonist in their [[VideoGameRemake remakes]], ''[=FireRed=]''/''[=LeafGreen=]'', with a party including a level 80 ''Pikachu'' and 70+ versions of all three original starters, Snorlax...and Espeon, for some reason. HGSS replaces the Espeon with a Lapras. The whole match has continous hail and all of there levels have been buffed up. ''Pikachu'' is level 88 now!]] In Emerald it's [[spoiler:Steven, the mandatory FinalBoss of the first two games of that generation, now cranked up to 11 as a BonusBoss. He has a similar team to the previous game (which was bad enough), but now they're all around level 80 rather than 50-60.]] Both fights are bragging rights only and give no real reward (although they are in fact repeatable, making them among the best spots to grind high-level Pokémon).
** The Battle Frontier in the various games can also be counted as a type of BonusDungeon -- they are all single player[[note]]Although some Generation 4 games had very basic online stuff, and Black and White added a rather roubust online component[[/note]] tournaments with various gimmicks, which also tend to be source of the better hold items, evolution trinkets, technical machines, etc. This means that if you are going for HundredPercentCompletion (or wish to be tournament viable) you will need to master these game motes. Unfortunately TheComputerIsACheatingBastard is in ''full'' and ''blatant'' effect.
* The Seraphic Gate in all three ''ValkyrieProfile'' games. ''VideoGame/ValkyrieProfile2Silmeria'' and ''[[ValkyrieProfileCovenantOfThePlume Covenant]]'' scales up the difficulty every time you beat it, and all require them to be beaten at least 10 times to get the InfinityPlusOneSword, the latter two being far harder due to reasons stated above.
* The ''StarOcean'' games all have at least one BonusDungeon. The Seven Star Ruins in the [[VideoGame/StarOcean1 first game]], Cave of Trials in the [[VideoGame/StarOceanTheSecondStory second]], as well as its GaidenGame, and Maze of Tribulations in the [[VideoGame/StarOceanTillTheEndOfTime third]], which jacked up the pot by adding Sphere 211, another 100-level dungeon, and the Urssa Cave Temple, a more puzzle-oriented Bonus Dungeon. The [[VideoGame/StarOceanTheLastHope fourth game]] brought back the Seven Star Ruins and added the Wandering Dungeon. Many of these dungeons share the same background music (slightly remixed).
* Yet another 100 floor dungeon exists in ''VideoGame/BeyondOasis''. There are prizes every 10 levels, and if you can make it all the way to the bottom without having to turn back to restock on supplies, your ultimate prize is an indestructible[[note]]most weapons break after limited uses, with the exception of your default dagger and a handful of well-hidden weapons[[/note]] [[InfinityPlusOneSword Omega]] [[FlamingSword Sword]].
* Mull's Dungeon in ''AtelierIris'' is only accessible after beating the game and contains a BonusBoss stronger than the final boss.
* The Chrysler Building in ''VideoGame/ParasiteEve''.
* The Moria Gallery from ''VideoGame/TalesOfPhantasia''. The later remakes expanded it with even more floors.
* Completionists playing ''VideoGame/TalesOfEternia'' will need to conquer Nereid's labyrinth, which involves five of your characters (including a couple squishy magic users), fighting solo against powerful boss enemies, followed by a difficult battle with the True Big Bad.
* ''VideoGame/TalesOfSymphonia'' has Niflheim, a TomeOfEldritchLore found in Sybak's library. The objective is to dive into the book's underworld and purge the evil from it. Its sequel has two of them, one of which requires you to be on a second playthrough. Bonus doesn't begin to describe it. The Japan-only PS2-version increases the difficulty of Niflheim further. It adds another five floors, and adds two additional bosses: [[spoiler: first, against a souped-up Magnius, Forcystus, and Pronyma on floor 10, and against Mithos' first form (minus wings), Kratos and Yuan on the 20th floor. Did I mention that you can only use three party members as opposed to four for the Mithos/Kratos/Yuan battle?]] Have fun!
* ''VideoGame/TalesOfVesperia's'' Memory Dungeon. The graphics are blurry, [[RealIsBrown it's brown]], and all the sound effects sound far away, like you're hearing them on a camcorder recording the actual video game. In here, you fight the party's memories, and with that, every enemy they've faced in the game. This makes for some weird situations, like StoneWall WhiteMage vs. [[spoiler: BrainwashedAndCrazy WhiteMage]] and GrumpyOldMan vs. [[spoiler:the other half of his SplitPersonality.]] Strangely, for a game whose characters lampshade many things such as {{CrackPairing}}s and DudeLooksLikeALady, this wasn't remarked about at all. The PS3 UpdatedRerelease ups the ante with the Garden of Izayoi, an [[MarathonLevel incredibly long]] dungeon with the gimmick of progressing through the floors by way of actual combat; once you defeat a group of enemies, paths on the battlefield open up for you to traverse to another battlefield with more enemies, and you make your way through several floors of mazes. There are plenty of new {{Bonus Boss}}es, including a horrific "monster" called [[spoiler:the Spiral Draco, the King of the Entelexeia]], which appears to have taken the title of "most difficult boss in the Franchise/TalesSeries."
* The 60-floor bonus dungeon of ''VideoGame/TalesOfDestiny'' is a remake of ''TheTowerOfDruaga''. A 10-floor version of the tower is the bonus dungeon in ''TalesOfTheWorld: Narikiri Dungeon 3''.
* Monad block in ''VideoGame/{{Persona 3}}''. The game's ultimate boss can be fought on the final floor.
** ''Persona 3 Portable'' has the Vision Quest, hosted by [[spoiler:Margaret, from ''VideoGame/{{Persona 4}}'']] in the Desert Of Doors from FES. While not a dungeon in the same sense as Monad, it does feature Bonus Boss versions of all the Full Moon Shadows as well as hidden boss that some are claiming is harder than [[spoiler:Elizabeth/Theodore]]. Yes, you get to fight [[spoiler:Margaret. And she isn't going to cut you -any- slack.]]
* Pork City in ''VideoGame/TheWorldEndsWithYou''.
* Chapter 8 in ''VideoGame/DarkChronicle'', which comes after defeating the main villain. Long story short, you go through an extra dungeon and end up fighting a hidden boss.
* ''VideoGame/ShinMegamiTenseiIIINocturne'' has both the Labyrinth of Amala and the Bandou Shrine. Completing the labyrinth gives you a sixth ending (and BonusBoss), and the shrine gives you the chance to acquire the [[InfinityPlusOneSword secret 25th Magatama]].
* Crossbone Isle of the first ''VideoGame/GoldenSun''. Not as difficult as a good deal of the examples listed already, but still can be a challenge. The second ''VideoGame/GoldenSun'' has Anemos Sanctum, Treasure Isle, Yampi Desert Cave, and the turtle's secret island, all of which have their own bonus bosses (which does not necessarily have to be beaten before taking on the Anemos Sanctum, but you might as well since you had to at least progress part of the way through each to get the Djinn inside before you could unlock it).
* ''VideoGame/GrandiaXtreme's'' Vortex Corridor.
* The original ''VideoGame/{{Grandia}}'' also contained no less than three bonus dungeon; the Castle of Dreams, the Soldiers Grave, and the Tower of Temptation, with the former two being available only for a limited time, and the latter being available to near the end of the game but nigh impossible to actually find. All of them have significantly ramped-up enemy difficulty (but absolutely abysmal experience payout), and all of them contain some of the most useful equipment for that point of the game.
* ''VideoGame/GrandiaII'' has the Raul Hills labyrinth, which hide the best defensive/recovery mana egg in the game.
* After beating the final boss in ''DigimonWorld'', there is a BonusDungeon that has no set location. The entrance is in one of many dungeon entrances around the map. Inside this BonusDungeon are color swaps of generic enemies that are extra powerful and at the end is the final boss once again, only this time at the highest health physically possible.
* Some ''VideoGame/DragonQuest'' games have added bonus opportunities as well, in each main series game starting with V and each remake starting with III.
** ''VideoGame/DragonQuestVI'' allowed you to defeat the equivalent of ''Satan'', upon which he beats up the normal final boss for you.
** ''VideoGame/DragonQuestVII'' features a BonusDungeon where you fight God. Literally. A second bonus dungeon features an easier bonus battle with the four elemental spirits seen earlier in the game, after which you get the chance to [[spoiler:invite God to live in your immigrant town]].
** ''VideoGame/DragonQuestVIII's'' BonusDungeon gives us the Hero's backstory, and a boss with several progressively different forms requiring different tactics to defeat- and his final form is styled to resemble [[spoiler:the final boss from the original ''VideoGame/DragonQuestI'', especially during his "psyche up" pose.]]
** The PSX/DS remake of ''VideoGame/DragonQuestIV'' includes a bonus dungeon which expands on the story, even allowing you to [[spoiler:redeem the [[ManBehindTheMan (apparent)]] BigBad, and the former final boss!]]
** The SNES/SFC remake of ''VideoGame/DragonQuestIII'' includes a new bonus dungeon which also adds a small piece to the story, enabling the hero to [[spoiler:revive his dead father as a wish granted by a [[DragonBall Shenlong]]-like dragon... and part of the bonus dungeon itself is a sky castle the game calls "Zenithia" according to translations, suggesting a connection to Dragon Quest IV]]. The GBC version takes it a step further with an additional, story-less dungeon and boss to fight after that one... ''if'' the player can collect every single randomly-dropped Monster Medal in the game.
** The PS2/DS remake of ''VideoGame/DragonQuestV'' includes a bonus dungeon unlocked after beating the main game. The final boss of ''VideoGame/DragonQuestIV'' lies at the end, with the difficulty significantly ramped up. Beating him unlocks the last [[MiniGame T'n'T board]] and beating ''that'' nets you the last two recruitable mons, who at this point are just for bragging rights. The real challenge is beating the BonusBoss in under fifteen rounds, which earns the final Knick Knack for your museum.
*** This same boss was also in the original Japan-only SNES/SFC version of Dragon Quest V, and was the first postgame bonus in the series.
** ''VideoGame/DragonQuestIX'' has a series of bonus story events, bosses, a few BonusDungeon areas (and several more randomly generated ones), and other content that can only be accessed after the main game "ends", including battling (and ''leveling up''!) the final bosses (and a few [[DiscOneFinalBoss less-than-final bosses]]) from the previous 8 games, but it really blurs the line since over half the playtime can be spent on postgame bonus content.
* ''BaldursGate: [[ExpansionPack Tales of the Sword Coast]]'' contains Durlag's Tower, a looming castle crammed full of thoroughly unpleasant enemies - and [[LudicrousGibs very large traps]].
* ''BaldursGate II: [[ExpansionPack Throne of Bhaal]]'' gives us Watcher's Keep, a five-story dungeon (plus one extra for the boss fight) featuring some of the most complex puzzles and challenging fights in the game, eventually climaxing in a fight with [[spoiler:Demogorgon]], who is not only, as a good BonusBoss should be, the most poweful enemy in the game, but [[spoiler:the most powerful being in the entire [[ForgottenRealms setting]]!]]
** Of course, some players created game mods making him ''harder'' just to ramp up the challenge further. Some people...
*** Which are nothing compared to the mods making the final bosses (of both the original and the expansion) easily 10 times harder to fight. And add a BossRush, because just fighting them one at a time is for sissies.
* The UpdatedRerelease of ''VideoGame/ChronoTrigger'' adds Dimensional Vortexes unlocked after the final boss, as well as [[ThatOneSidequest the Lost Sanctum]].
** Even the original SNES version of the game had the Black Omen, an optional dungeon (although necessary to access NewGamePlus) that can, through the magic of TimeTravel, be cleared three times for maximum loot.
* ''[[Franchise/DotHack .hack]]'' gives us the Bonus Dungeons after the end of every game. In ''[[VideoGame/DotHackGU G.U.]]'''' one of those is called the [[NamesToRunAwayFromReallyFast Forest of Pain]]. How utterly appropriate.
* ''VideoGame/PokemonMysteryDungeon'' loves these. Of particular note is Purity Forest from the original pair of games. You can only bring one Pokémon in, which is brought down to level one. Also, all your items and money not in storage are destroyed. Good luck.
** Similar to Purity Forest is Zero Isle in the second pair, which is divided up into four parts. Zero Isle North simply doesn't give you any EXP but has some strong foes, but South, East, and West drop you down to level one at the start, you can't bring items to Zero Isle South or West and can only bring 16 items to Zero Isle East, and Zero Isle West also limits you to just the one Pokemon!
*** And let's not forget Destiny Tower in Explorers of Sky, in which you can only enter with one Pokémon, which is dropped to level one, enter with no items or money, all IQ skills nullified, hidden traps remaining hidden (not to mention the horrifying Random Traps and Grudge Traps), and the inability to be rescued if you faint!
*** Likewise, there's Zero Isle Center in Sky. You can only bring 16 items, it doesn't give you any EXP, has some dangerous foes at Level 90-99, hidden traps remaining hidden, Random/Grudge Traps, and no rescuing. Have fun with that.
*** Path of No Return in ''Gates to Infinity'' is one of the few dungeons with the absent-for-most-of-the-game [[WizardNeedsFoodBadly hunger system]]. It's also a 99-floor dungeon that only lets you take one party member and reduces them to level 5, and you can't take items or money or recruit anybody. There's also Slumbering Path, which at least lets you take up to 4 party members.
* Probably about a third of ''VideoGame/{{Xenosaga}} 2'' was side-quests and another third Bonus Dungeons.
* ''VideoGame/ShirenTheWanderer'' has a bunch of extra dungeons you can take on after beating the main game, including the Kitchen God Dungeon (a special dungeon where you start with Bufu's Cleaver, a weapon that can turn enemies you kill with it into meat), the Cave Behind the Scroll (a possibly shorter dungeon where you start with a Trap Armband, which enables you to pick up and place traps and use them against enemies, as well as gain experience for killing them with traps), Fay's Final Puzzle (a 99-floor marathon where even herbs and scrolls that you find will be unidentified), the Tainted Path (''another'' 99-floor dungeon, with very strong monsters and a boss at the end), the Ravine of the Dead (a 50-floor frolick with tougher monsters, ''fake stairs'', and lots of Monster Houses), and the Ceremonial Cave (a 30-floor labyrinth with tough monsters and another boss). The first three of these dungeons don't allow you to bring any items or money, and you can't bring companions into Fay's Final Puzzle.
* The "Another Goddess" quest in ''VideoGame/HalfMinuteHero'', aside from being very long for the game's scope (most levels last about 30 seconds, while this one will take a good five minutes), harkens to another Marvelous Entertainment-created RPG: ''ValhallaKnights'' (the title even changes to reflect this). It's accessible during normal play, but because of the major change in style, the Time Goddess urges you to walk past it, on to the next quest. In order to actually play it, you have to defeat [[OneHundredAndEight 108]] bosses first. Harsh.
* There's six of the things in ''VideoGame/LastScenario'', seven if you count the one that's really just a sequence of four bosses. Luckily, all of them give you some ''very'' nice rewards.
* ''VideoGame/BlueDragon'' has the [[ExpansionPack downloadable]] Shuffle Dungeon, which gives you several new items to collect and some new monsters to fight.
* ''VideoGame/{{Torchlight}}'' has the Shadow Vault, known in FanSpeak as the Infinite Dungeon.
* The ''VideoGame/MegaManBattleNetwork'' series is known for its expansive bonus dungeons, taking the form of huge mazes with doors that must be unlocked by completing some objective elsewhere in the game. [=BN2=] had [[spoiler: [[ManBehindTheMan WWW Area]]]], 3 had [[ExactlyWhatItSaysOnTheTin Secret Area]], 4 had [[BonusLevelOfHell Murkland]], 5 had [[StormingTheCastle Nebula Area]], and 6 had the Graveyard, a SuperMode BossRush.
* An early example in ''VideoGame/SwordOfVermilion''. Unlike all other dungeons in the game, nobody ever asks you to visit, or even mentions the existence of the dungeon where the [[InfinityPlusOneSword Death Sword]] is found.
* ''PhantasyStarIV'' had a couple of optional dungeons that contained some nice loot, and in one case a ContinuityNod to the previous installment.
* The Server Room in ''{{Opoona}}.'' It opens up about midway through the game, but actually ''challenging'' it at such a point is not especially advisable. In addition to containing {{Mooks}} that are extremely fast, can heal themselves, and prevent you from using your Force (magic), the battle stages are full of bombs, which prevent you from using just about any hit-all abilities lest they explode. (And if they do so, they'll knock off about 100 HP--about three or four is enough for a TotalPartyKill.) And if ''that'' doesn't kill you, the room is also home to Salamanders, one of the game's most brutal BossInMookClothing monsters. However, you can leave at any time to save and heal without losing your progress.
* The VideoGame/FalloutNewVegas DLC ''Lonesome Road'' adds the Long 15 and Dry Wells maps, which are unlocked by launching nuclear missiles at NCR and Legion territory, respectively.
** Also, the Courier's Mile, an irradiated crater created by the missile launched from Ashton that is home to Irradiated Deathclaws and Irradiated Marked Men, the latter of which regenerate HP from the radiation, as well as two of the warheads required for the Warhead Hunter achievement.
** The main game has Deathclaw Promontory, home to the highest concentration of deathclaws in the game, as well as a suit of T-51b armor, a Multiplas rifle, and a tri-beam laser rifle. Also in the promontory is a suit of Enclave armor lacking a helmet, the latter of which can be found in Silverpeak Mine, guarded by the [[BonusBoss Legendary Cazador]]
*** Speaking of Deathclaws, there's also Dead Wind Cavern, at the end of which is another BonusBoss, the Legendary Deathclaw, guarding the unique grenade machine gun [[ICallItVera named Mercy]].
** Some of the optional non-story dungeons in ''VideoGame/{{Fallout 3}}'' may count, such as Deathclaw Sanctuary, the National Guard Depot, Fort Bannister, which also houses a BonusBoss, and the Dunwich Building.
* VideoGame/{{Wasteland}}, the original Post-Apocalyptic RPG, had this in the form of [[ExactlyWhatItSaysOnTheTin Finster's Head]]. A one-man-solo "dungeon" ([[spoiler:VR sim, actually]]) in a party-oriented game that comes right after what passes for the game's WhamEpisode can catch you by surprise with its (entirely optional) BonusBoss that yields the largest XP boon in the whole game (DOUBLE that if you kill him in melee) and an inventive puzzle maze.
* ''VideoGame/KingdomOfLoathing'' has the Sea, which unlocks after you beat the game's BigBad, the Naughty Sorceress. It's full of tough monsters, exploring it initially requires you to wear an accessory that gives you a serious penalty to item drops and initiative, you can only take familiars that can breathe underwater with you, and unless you have a specific effect gained only by consuming certain items found in the Sea itself, it costs two adventures to explore a zone once. There's also the Clan Dungeons (Hobopolis, the Slime Tube, Dreadsylvania, and the Haunted Sorority House), which are intended for high-end players and full of tough monsters; and Fernswarthy's Basement, which is full of increasingly difficult challenges, but offers big stat bonuses every five levels, and powerful consumables that appear every 100 levels.
* ''VideoGame/TalesOfXillia'' The dungeon interior uses a similar format like that of ''TalesOfVesperia'', in which that the player will go through what seems to be areas they've been to.
* ''VideoGame/TalesOfXillia2'' This dungeon requires a completion of the game (once), a special key item and a trip to the Spyrius Corporation building. The dungeon poses as a normal warehouse in Drellin, but traversing it is a whole different matter. You will be faced with a dark dungeon. With a shadow silhouette palette of the enemies. The bosses itself resemble Ludger's team ending with two hard battlers at the end.

[[/folder]]

[[folder: Shoot Em Ups ]]

* The ''VideoGame/{{Touhou}}'' series, unusually for ShootEmUp games, has pretty much made a tradition out of this. ''Perfect Cherry Blossom'' went one step further by having ''two'' Bonus Dungeons.
** Alice and Marisa's WrongGenreSavvy in ''Subterranean Animism'' leads to the page quote in that game's extra stage.

[[/folder]]

[[folder: Survival Horror ]]

* ''TheSuffering'' features a pseudo-bonus dungeon in Chapter 19. If you deviate from the path that the AI leads you on, you can find a cave with a few [=NPCs=] and a slew of overly powerful monsters. The reward? The final component to the super-secret Flamethrower weapon (which certain exploratory players will have discovered several chapters prior).
* ''VideoGame/{{Ib}}'' has one that's accessible near the end of the game if you've [[NewGamePlus gotten a 'survival' ending on a previous playthrough]]. It doesn't have super-tough monsters, but it does have a ton of puzzles that ding your LifeMeter every time you fail to solve them and you're given only one chance to refill your life meter for the bulk of your stay there.

[[/folder]]

[[folder: Turn-Based Strategy ]]

* The Hellgate from ''TacticsOgre'' was 100 levels deep, and interestingly actually tied into the plot, as the bottom level was where one of the [[BonusBoss villains]] in the game had retreated to. Beating him didn't change the main plot of the game, though. In order to get the ultimate "bragging" item in the game, one had to go through the Hellgate twice, as well as get 4 specific weapons from special encounters with recolored monsters.
* Beauty Castle and the Alternate Hell from ''VideoGame/DisgaeaHourOfDarkness'', as well as a world within every item which is generated randomly. Fittingly, the Alternate Hell was the BonusDungeon for the previous game, ''LaPucelleTactics''. There is a similar version in ''PhantomBrave'', which is yet another in the NipponIchi line of TurnBasedStrategy games.
** Also fitting in that the Beauty Castle is the last dungeon in another NipponIchi game, RhapsodyAMusicalAdventure.
* ''Franchise/FireEmblem'': ''[[VideoGame/FireEmblemTheSacredStones The Sacred Stones]]'' has two of these: the Tower of Valni, and, more fitting, as it is only available toward the end of the main game, the Lagdou Ruins.

[[/folder]]

[[folder: Wide Open Sandbox ]]

* After trudging through Zero's [[ThatOneLevel first two missions, which involve shooting down/fighting with toys on a very tight timer]] in ''VideoGame/GrandTheftAutoSanAndreas'', you are treated to...an RTS mission. However, it is probably the most fun mission in the game since it's virtually impossible to screw up, and hearing David Cross cheer you on when you do well at it creates quite the fuzzy feeling. Oh, and one of the previous scrappy levels becomes infinitely replayable after you beat it, although there is now no longer a penalty for failing it.

[[/folder]]

[[folder: Non-Video Game Examples ]]

* The [[http://adventuretime.wikia.com/wiki/Dungeon_Train_(location) Dungeon Train]] from ''WesternAnimation/AdventureTime'' has all the halmarks of a Bonus Dungeon, such as being extremely long, having unique bosses, but also containing numerous [[PaletteSwap Palette Swaps]]. Finn finds the place so much fun that he almost decides not to leave!
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