A level in a video game which is an altered version of an area you were in earlier. Sometimes you're visiting the same world in different time periods - be they separated by days, months or centuries. Other times, you're visiting another version of the area in an AlternateUniverse - maybe even a BizarroUniverse.

Such areas nearly always happen to contain ChaosArchitecture, which 'explains' why the TempleOfDoom that you visited in the present day has a radically different floor layout ten years in the future.

May overlap with DarkWorld, might be used for DualWorldGameplay. Not to be confused with MirrorUniverse. Also not to be confused with RemixedLevel, which is the exact same level with minor differences; this is an "alternate" version of the level, or one with intentional similarities.

If, however, the world is ''literally'' mirrored (i.e. flipped left-to-right), then it is a LevelInReverse
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!!Examples:

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[[folder:Action-Adventure]]
* The upside-down castle in ''VideoGame/CastlevaniaSymphonyOfTheNight''.
* ''VideoGame/CastlevaniaHarmonyOfDissonance'' is somewhat similar to ''Symphony of the Night'', except the player does not visit the second castle after visiting the first, but goes back and forth between the castles throughout the game, becoming aware of it around halfway through. [[spoiler:The castle in which you fight the final battle helps determine which ending you get]].
* Done to great effect in ''VideoGame/DayOfTheTentacle''. The game's three protagonists are stuck in the same mansion, but one is in the present, one is 200 years in the past and one is 200 years in the future. A number of puzzles involve taking advantage of various objects that exist in the mansion in more than one time.
* In the old PC AdventureGame ''ViedoGame/DarkSeed'' and its sequel, you point and click your way through the normal scenes in town, then go through a mirror to visit those places in a world designed by Creator/HRGiger.
* ''VideoGame/DevilMayCry'' had a mirror you could pass through. Said Mirror World was horrifying with the bloody color, tilted camera angle and the shifting water effect on everything. Not to mention the random enemies that '''THROW THEIR EYEBALLS AT YOU.'''
* ''GhostbustersTheVideoGame'' (2009) had this in the Sedgwick Hotel. When you revisit it for chapter 5, it is undergoing extensive remodeling to repair the damage done, ironically, by the Ghostbusters themselves in the first chapter, but this still doesn't explain why some of the hallways on the 12th floor are entirely different now. (The lobby, however, is brilliantly consistent.) Perhaps justified in that the [[spoiler: Spiderwitch]] has been doing some extensive remodeling of her own on floor 12, warping it into a twisted trans-dimensional abomination-world made mostly of cobwebs and corpses wrapped in said cobwebs. [[spoiler: Still, it's exceedingly strange that in the first chapter room 1221 does not exist, while rooms 1219 and 1220, right around the corner from it in chapter 5, do. The left turn made after room 1220 to get to 1221 in chapter 5 leads to a solid wall in chapter 1.]]
** [[spoiler: Although the 12th floor layout is indeed different, room 1221 does exist in the first chapter. Using your PKE meter and goggles you will actually find [[TheDevTeamThinksOfEverything a ghostly image of a spider on the door when you walk past it.]] Nice ForeShadowing...]]
* ''VideoGame/IllusionOfGaia'' for the SNES contains one temple, the Sky Garden, which serves as a variation of this. Basically, you must jump from the "right side up" portion of the garden to the "upside down" portion of the garden, using the various "jump" points to navigate past obstacles in the maze and hitting certain switches that have an effect on the obstacles on the opposite side. No real explanation is given on why, when you jump off a ledge, you don't fall off the edge and plummet to the Earth below (not to mention how you can walk upside down). [[MST3KMantra It doesn't take away from the gameplay or story, though, so don't worry about it.]]
* ''VideoGame/LegacyOfKain: Defiance'' often had the two protagonists exploring the same locations while separated by five hundred years. The Spectral Realm may also qualify.
* ''VideoGame/TheLegendOfZeldaALinkToThePast'' had the DarkWorld, where a puzzle required you to drain water from one world and use the fact it would fill the other.
** ''VideoGame/TheLegendOfZeldaMajorasMask'' has the Stone Tower Temple, which you must flip from right-side up to upside down. Conditions in the "heads" version affect conditions in the "tails" version, and vice-versa.
** The Past in ''[[VideoGame/TheLegendOfZeldaOracleGames Oracle Of Ages]]''.
** The future in ''VideoGame/TheLegendOfZeldaOcarinaOfTime''. Certain actions such as planting seeds in the past have effects on the future timeline.
* ''VideoGame/LuigisMansion'' had the Hidden Mansion, which, in the PAL version only, was a mirrored version of the Normal Mansion made more difficult.
* Dark Aether in ''VideoGame/MetroidPrime 2: Echoes''.
* ''VideoGame/ZackAndWikiQuestForBarbarosTreasure'' has one level in the [[BigBoosHaunt Ghost House]] with a mirror, that hides the treasure from you. [[spoiler: your mirror image is alive, and keeps moving it in between you going through tunnels]].
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[[folder:Fighting Games]]
* Certain areas of Subspace Emissary in ''VideoGame/SuperSmashBros Brawl'' had you shifting between daytime and sunset of the same level, using it to remove an obstruction -- on both sides -- from one side, that would be indestructible on the other. It probably isn't a coincidence that this game and ''Kirby Super Star'' had the same designer.
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[[folder:First Person Shooters]]
* In the ''VideoGame/{{Marathon}}'' GameMod ''Marathon EVIL'', the penultimate level has a [[AlienGeometries "5d space"]] portal which leads to a mirror version of the level occupying the same space.
* Map 4 of ''TNT: Evilution'' has two versions of the same map which you swap between by going through a portal. However, you don't have to enter the DarkWorld equivalent to finish the level.
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[[folder:Platformers]]
* The four different seasons of Click Clock Wood in ''VideoGame/BanjoKazooie''.
* Utilized in ''VideoGame/{{Braid}},'' most {{Mind Screw}}ingly in the final level.
* "Zoovania" in the [[{{Uberwald}} Transylvania]] world in ''[[WesternAnimation/LooneyTunes Bugs & Taz]]: Time Busters''. If you visit during the day, it's a normal zoo. Visit at night and it's changed; most notably all the animals turn into monsters. You can toggle day and night from outside the zoo.
* Day and night versions of Fungi Forest in ''Donkey Kong 64''.
* Haven City in ''VideoGame/JakIII'' has almost completely been taken over by enemies, but the layout of areas is the same as in the second game..
* Floria in the ''VideoGame/KirbySuperStar'' game ''Milky Way Wishes'' had you shifting between four seasons of the same level to get past barriers present during one season but not another.
* In ''VideoGame/LaMulana'', almost all parts of the ruins had a "front side" and a "back side." One set of front and back areas in particular is the Twin Labyrinths, an area whose front and back side are mirror images of each other.
* A 3D game based on ''PhineasAndFerbTheMovieAcrossThe2ndDimension'' has the playable characters going through two dimensions on each level.
* A major part of ''VideoGame/PrinceOfPersiaWarriorWithin'' takes place in a ruined fortress both in the present and the past. You will often need to travel between the times to find away around obstacles.
* World 6 in ''VideoGame/{{Purple}}'' is a set of five (not including 6-6 and Final Destiny) stages replicating the looks of previous worlds with neons. Stage 6-1 is an almost exact copy of stage 1-1.
* ''VideoGame/RatchetAndClankUpYourArsenal'' has an actual Mirror cheat. Levels can be played as mirror images of themselves.
* ''VideoGame/SonicTheHedgehogCD'''s Past, Present, BadFuture and GoodFuture versions of the same levels.
* A ''lot'' of the Special Levels in ''VideoGame/SuperMario3DLand''.
* ''VideoGame/SuperMario64'' had Tiny-Huge Island, in which you could enter pipes and travel to the other world. Everything was exactly the same, save for size.
* Subspace from ''VideoGame/SuperMarioBros2''.
* ''VideoGame/SuperMarioBros3'' has a level with doorways that lead to a mirror version of that level where the enemies are normal-sized (normally they're huge because the level is in Giant Land)
* Flopside in ''VideoGame/SuperPaperMario'' is very literally a mirror world: you get to it through a mirror, and it's a reversed version of the first town. The people are even the opposite of the people in Flipside. For example, Flipside has a grandmother who gives good advice, which her granddaughter says she is following while doing just the opposite, while Flopside has a grandmother who gives bad advice, which her polite, obedient grand-daughter is willing to follow.
* ''VideoGame/{{Portal 2}}'''s beginning shows the first test chambers of the first game, but rather destroyed and overgrown.
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[[folder:Racing]]
* ''VideoGame/MarioKart'' has had Mirror Mode since ''VideoGame/MarioKart64''.
** ''VideoGame/DiddyKongRacing'' does this as well in [[NewGamePlus Adventure Two]]; all tracks are mirrored.
* The first three circuits in LegoRacers are a series of creative tracks based on various Lego themes, with each track having a specific character to represent it and a champion somehow connected with the theme of the first track representing the circuit overall. Then the next three circuits are the exact same racetracks as before, but in reverse order and mirrored, with the champion racer being connected to the theme of whatever track was previously last.
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[[folder:Role Playing Games]]
* The entire world in ''VideoGame/DarkCloud 2''. The world you enter by going through the red Time Gates is the same world you're already in, but 100 years in the future. Since so much time passes, the differences between the two can be...striking.
* Amaterasu Server in ''Franchise/{{Digimon}} World 3''.
* ''VideoGame/DragonAgeOrigins'' has a few different examples of this, depending on which origin the player chose. Dwarf nobles, dwarf commoners, mages, and city elves will all revisit their homes about one year after they left and much has happened in the interim, while Dalish elves will revisit the same forest they grew up in, but with a different clan of Dalish after their own clan left.
* ''VideoGame/EarthBound'' has Moonside, which is a twisted, alternate reality version of Fourside.
* ''VideoGame/NeverwinterNights'' had a temple that you had to enter in the past in order to fix something in the present. You went in in the present, found a way to the past so you could change something, then went back in in the present and your problems were solved.
* ''VideoGame/NeverwinterNights2: Mask of the Betrayer'' combines this with DarkWorld, launching the player into Shadow Plane versions of some locations in the main world.
* The Caverns of Time in ''VideoGame/WorldOfWarcraft'' are basically this trope mixed with TimeTravel. You travel to past versions of some in-game zones and dungeons to witness major lore events. They are mostly an homage to earlier games in the ''VideoGame/{{Warcraft}}'' franchise, but the latest bunch added in a ''Cataclysm'' content patch are integral to the main plot.
** ''Warlords of Draenor'' adds Draenor, which is ''The Burning Crusade'''s Outland before the planet exploded. Draenor was previously visited in the RTS ''Beyond the Dark Portal'', but a lot has [[{{retcon}} changed]] since then.
* Nightfallen Jahai in ''VideoGame/GuildWars'' is a dark, Realm of Torment version of the Jahai Bluffs zone, with the same shape (including zone entrance locations), but terrain types and inhabitants appropriate to the Realm of torment. It is implied that this is what the real Jahai will be like if Nightfall occurs (which the players are trying to prevent.)
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[[folder:Survival Horror]]
* ''VideoGame/EternalDarkness'' is 12 levels long, which is to say it's four areas set in different time periods, led by different characters, with different obstacles\items\enemies\routes\etc.
* ''VideoGame/GhostHunter'' has two different versions of the [=DeMontford=] Mansion. There's a Weird version and an Evil version, so named in the save file titles. There's also a normal version, but only a few rooms of it are visited.
* In ''VideoGame/{{Penumbra}}: Black Plague'', you visit [[spoiler: a darker, much creepier version of the very first area in the first game, "Penumbra: Overture"]]
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