So, you've finally beaten World 4 of your 8-World game! You're halfway done!

Wait... why does World 5 look ''exactly'' [[CopyAndPasteEnvironments like World 1]]? And why are all the enemies replaced with harder, faster ones? And the time limit's smaller, too! And, what the heck, your HP Cap is lower?? What's going on here?!

Welcome to the Hard Mode Filler. Unlike a standard difficulty setting, this is when a game forces you to replay something earlier at a harder difficulty ''during the same playthrough''. It also counts if the game doesn't actually give you an ending after beating an easier difficulty, instead just unlocking a harder difficulty which the end of the game lies behind. Sometimes it shows you interesting new dimensions behind older levels, while other times it is simply a case of the developers being lazy and not wanting to design more levels.

Compare SecondQuest, where this happens to the entire game after the first playthrough is over. See also WhereItAllBegan, when you have to return to an earlier area as part of the story. Sometimes a BossRush works the same way, but you're only redoing the bosses.

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!!Examples:
* ''Franchise/SuperMarioBros'':
** ''VideoGame/SuperMarioBros1'' - While you didn't have to replay the entire game at a harder difficulty, five of the later levels were exactly the same as earlier levels except with harder enemies, smaller platforms, and sometimes Bullet Bills flying through the air. And more and/or longer fire bars in the castles, too. This is because there wasn't enough [=ROM=] to handle more unique areas.
** In the original FDS version of ''VideoGame/SuperMarioBrosTheLostLevels'', you have to play through the first eight worlds several times to reach Worlds A through D, the true final stages. And even some of ''those'' are just harder versions of existing levels.
** ''VideoGame/SuperMarioBros3'' did this with the Koopaling bosses. The later worlds had the same type of boss battles, except that the ground would shake and stun Mario whenever the boss would jump. Also counts for the Boom Boom battles, which were all the same, save for extra obstacles thrown into the room, and sometimes he would get either wings or steroids to jump around the room wildly. At least the Koopalings all had different sprites.
** ''VideoGame/SuperMarioWorld'' did this with the bosses, too: each of the first three had a harder version. And there were also a total of three [[SmashingHallwayTrapsOfDoom Smashing Mallet Traps of Doom]] rooms that were identical in layout, except the second one was cluttered with spinning saw blades and the third one had lava pits.
** Most of the Prankster Comets in ''VideoGame/SuperMarioGalaxy'' just make a previous mission harder for a new Star. Speedy Comets give you a time limit and take away checkpoints, Fast Foe Comets make hazards move faster (thankfully you're usually only forced to redo a ''segment'' of a mission), and Daredevil Comets make you redo a boss, or even a whole mission, with one hit point (turning Bouldergeist from a relatively easy foe to ThatOneBoss). However, the Cosmic Comets (a race against a shadowy doppelganger) and Purple Comets (a coin hunt) can still be pretty unique.
** ''VideoGame/SuperMarioGalaxy2'' has 120 Green Stars after you've defeated the game which are hidden throughout the levels and require the player to make progressively harder jumps to reach them. And the last star is a real pain.
** ''VideoGame/SuperMario3DLand'' reused levels and parts of levels for the bonus worlds, only with some extra variable like a 30-second time limit that gets replenished by beating enemies and collecting clocks. In particular, the DualBoss battle against [[RecurringBoss Boom Boom and Pom Pom]] at the end of World 7 is reused in the BrutalBonusLevel of Special 8. The only differences are that A) Boom Boom now leaves a fire trail like when you fought him at the end of Special 6, and B) Pom Pom's theme is playing instead of Boom Boom's.
* ''BoulderDash'' for the NES did not show you the credits until you beat four progressively harder versions of all six worlds in the game, increasing diamond quotas, decreasing time limits, and changing some parts of the level. Getting to World 7, you would find that it's just a harder version of World 1.
* ''PunchOut'' for Wii has Title Defense mode. You have to refight all the characters from the game with remixed movesets, and you have less HP. Also, ''Mike Tyson's Punch-Out!!'' for the NES makes you re-fight Piston Honda, Bald Bull and Don Flamenco a second time in [[TookALevelInBadass tactically riced up form]] with halved HP.
* A lot of ShootEmUp games make you replay at a harder difficulty after you finish it once, a feature called "loop" by fans.
* The entire ''VideoGame/GhostsNGoblins'' series is infamous for this. Most of the games in the series forces the player to play through the entire game twice in order to fight the final boss and see the ending. The second time the player play through the game, they're forced to seek a special weapon required to defeat the final boss.
* The original Pilotwings did this. When you reached Area 5 after your first helicopter mission, the game became Pilotwings Expert and you had to play through the same four areas as before, except a LOT tougher.
* ''VideoGame/MetroidPrime: Hunters'' did it with bosses. Aside from the final bosses, there were only two bosses in the game and you had to fight them both four different times, each time with harder difficulty.
* ''Star Prince'' and the first two ''Robot Ninja Haggleman'' games do this in ''RetroGameChallenge'', as does Muteki Ken Kung Fu in the sequel, although there's a code to begin the game from the second playthrough, similar to [[VideoGame/TheLegendOfZelda Zelda 1.]]
* ''VideoGame/RhythmHeaven's'' "boss" stages are remixes of older games glued together into one harder game. After the 60% mark, even normal levels are just variations of older levels. The remixes and variations are pretty different, but the marketing of "50 minigames" is questionable. For the record, ''Heaven'' for the DS has 24 minigames, 10 remixes, 16 hard versions of minigames, 6 endless games, 8 guitar songs, and 6 "rhythm toys", while ''Fever'' has 28 minigames, 10 remixes, 12 hard versions of minigames, 5 endless games, 4 toys, 4 remakes of games from ''Rhythm Tengoku'', 8 two-player versions of minigames, and 5 two-player endless games.
* Rare's ''[[VideoGame/GoldenEye1997 GoldenEye]]'' has two Surface missions. The 2nd is at night and ThatOneLevel to some fans.
* ''VideoGame/ThemePark'' boiled down to this. After the first few missions, every level boiled down to the same thing, but suddenly the customers spent less money, inflation was much higher, and everyone began hating you
* Since the levels in the original ''Populous'' were generated with an algorithm, they often fell into this (and SchizophrenicDifficulty) -- you'd invariably get levels resembling early ones but harder. Such filler levels were usually bunched together, though you could skip past them if you earned a good enough score.
* ''[[BitTrip Bit.Trip Void]]'' was very guilty of this during the songs Ego and Superego, repeating lots of the beat patterns from earlier songs but throwing in some extra white beats to make it harder.
* Some levels of ''VideoGame/{{Lemmings}}'' were repeats of earlier levels with differences in time limit, skill set, and other things. The most famous is the repeat of "We All Fall Down" on each difficulty, adding more Lemmings each time. In some cases this presents the opportunity that an efficient strategy you used on an early level could be reused later, eliminating whatever challenge may have been intended.
* Flash game ''ThisIsTheOnlyLevel'' has a variant of this trope. There are 30 stages with the same level except there is a catch every stage, like inverted controls, barriers, and creative ways to unlock the gate to the 'next' level. And then there's the unlockable FML mode in the second game which involves random spikes and random changes of the level layout that will almost always result in your immediate demise. "[[FunWithAcronyms FML]]" officially stands for Frustratingly Manipulative Level, but rest assured that you '''will''' be [[ClusterFBomb spewing the more common kind of FMLs]] as you try to beat it.
* ''[[VideoGame/NineteenFortyTwo 1942]]'''s second half is a rehash the first half with a higher difficulty.
* In ''VideoGame/TwinCobra'', stages 6 through 10 are the same as 1 through 5 with different, much harder enemies and bosses. And then the whole game [[EndlessGame loops indefinitely after that]], [[NoEnding without so much as a "congratulations"]].
* ''CrisisCore'' is also guilty of this, with a lot of the later harder missions taking place in what looks like the exact same dungeon as the easy missions, except you have more ground to cover, and the PaletteSwap enemies get more deadly.
* In ''VideoGame/AstroBoyOmegaFactor'', Astro [[KillEmAll fails to save the world]] after defeating Pluto and the world's strongest robots. However, the Phoenix shows up and grants Astro TimeTravel so he can restart his adventure and SetRightWhatOnceWentWrong. For some reason, everything deals double damage now, and enemies have better reaction times and more hitpoints. Replaying through this unlocks the real final stage and the GoldenEnding.
* ''VideoGame/MegaManBattleNetwork 4'' is a particularly infamous example of this. After beating the main story once, loading a save file prompts the player to start a NewGamePlus on a higher difficulty level where all their chips are carried over. Unfortunately, all of your key items used to access shortcuts are lost on each new playthrough, forcing you to get them all over again. And then there's the post-game area, [[BonusLevelOfHell Black Earth]], which, due to [[BonusBoss Bass]] being unfightable until you get all 6 souls, which in turn requires aforementioned 3 playthroughs, has to be done on the highest difficulty setting. It's understandably regarded as the worst game in the series.
* The developers of ''GuildWars'', once realizing that everyone and their grandmother had finished the 3 campaigns and ran out of things to do, introduced a "new" dimension to the game to encourage players to actually play the same missions and areas with faster and harder monsters, and they literally called it hard mode. And then to make hard mode, well, easier, they introduced more [=PvE=] skills in the expansion, Eye of the North, that only players can use to defeat the bigger and badder monsters.
* Some earlier games on the SegaMasterSystem, like ''Safari Hunt'', ''Ghost House'', or ''My Hero'', only had three levels, and basically followed this trope to the letter.
* The Challenge Chambers in ''VideoGame/{{Portal}}'' invoke this trope, taking several of the prior testchambers and making changes to increase difficulty, such as reducing the number of [[PressurePlate Weighted Cubes]] you have available, or making certain walls un-portal-able.
* To see the true ending of ''Arkista's Ring'', you must play through all 31 levels four times; the enemies become extremely fast and tough in the later loops, especially the ninjas. After the first loop, you receive the titular ring, which [[WalkItOff restores HP with every few steps]].
* In ''WorldOfWarcraft'', "Heroic" dungeons are earlier dungeons tuned to a difficulty for a moderately well equipped player at the current level cap. For the most part, the enemies hits harder, drop better loot, etc. However, some of them add new boss abilities, or an [[BonusBoss additional boss]]. Cataclysm has brought this one step further by introducing heroic versions of popular content from previous expansions, as well as the standard "Hard Mode" that it has been used for previously. The fanbase seems to be split between fans and critics of the system: some older players are happy to replay the "golden age" content, and newer players may be excited to see this hyped content for the first time (it can be hard to find a group for a mid-level dungeon from which the rewards would be obsolete after just a little LevelGrinding), but other longtime players think Blizzard is trying to exploit nostalgia to pump out relatively easy-to-design, cheap content.
* {{Rift}} uses the same method as ''WorldOfWarcraft'' with expert dungeons, which are exactly the same thing in idea and execution.
* The arcade version of ''VideoGame/{{Commando}}'' has eight semi-unique levels, but has NoEnding and [[EndlessGame starts over after you "complete" it]], while the NES version, which has only four unique level designs, has a AWinnerIsYou ending after 16 levels (four loops).
* ''VideoGame/BlackAndWhite'' has an interesting example with world 4. It is world 1, but supremely messed up by Nemesis. You have to destroy three well protected stones which cause [[KillitwithFire fireballs to assault your village regularly]], [[ShockandAwe lightning to strike randomly]], and [[ArsonMurderandJaywalking constant rain]].
* ''VideoGame/TheLegendOfKage'' has you play through the levels in four seasons, with increasing difficulty each season. After that, [[EndlessGame you start back in spring]].
* A variation occurs in ''VideoGame/{{Zuma}}'', which will give you a new color ball and increase the speed by repeating the same three worlds over and over again. For the first three repetitions, an extra level per world might seem to [[AvertedTrope avert]] this, but it's played completely straight between the third and fourth repitition.
* The ''VideoGame/{{Raiden}}'' games restart at a higher difficulty, and ''IV'' has a TrueFinalBoss at the end of the second loop.
* In ''VideoGame/KingOfTheMonsters'', you fight the five other monsters and a clone of your player character... and after beating him, you do it all over again except the enemies have more health and the locations are slightly swapped.
* In the original ''RollingThunder'', the latter half of the game consists mainly of harder versions of the first five stages, with additional traps and enemies not in the early stages. Only Area 9, the penultimate stage, is completely original and not a rehash of an earlier stage. The arcade version even has an optional stage select feature that allows players to start off at any of the first five stages.
* ''VideoGame/Kirby64TheCrystalShards'' has something that is either a very mild example or a subversion. The first stage of the final planet is more or less a PaletteSwap of the very first stage (including the color-coded "hit this barrier with this ability to remove it" being a different color), but any difference in difficulty is negligible at best, turning this into a BreatherLevel.
* The last three levels of ''VideoGame/HaloCombatEvolved'' are repeats of earlier levels, with minor variations added. For example, level 9 is basically level 3 with the Flood and some damage to the ship added, between what are basically level 5 reversed, at night, and with the Flood, and level 1 with more damage to the ship, more areas opened up, and, you guessed it, the Flood.
* ''VideoGame/SonicColors'' does this with the bosses; the bosses for Planet Wisp, Aquarium Park and Asteroid Coaster are harder versions of the bosses for Tropical Resort, Sweet Mountain and Starlight Carnival, respectively.
* In ''VideoGame/SonicHeroes'', Egg Albatross is a harder version of Egg Hawk (heck, the Egg Hawk is sat atop the Egg Albatross, destroy the latter enough, and the last part is a fight against Egg Hawk), You fight another team battle in the fifth zone, much like the team battle in zone too, and then the sixth boss, Robot Storm, is again a massive {{Mook}} fight, much like Robot Carnival was.
* ''VideoGame/MegaMan III'' - The four Doc Robot stages (which takes place after the eight initial stages, but before Dr. Wily's fortress) are just redesigned versions of Spark Man's, Needle Man's, Shadow Man's and Gemini Man's stages.
* ''VideoGame/{{Alpiner}}'' had eighteen levels, consisting of the same six mountains repeating with faster falling hazards and decreasing time limits.
* ''Munch Man'' (a ''Pac-Man'' clone for the TI99) had 20 levels. The next 20 were the same maps with faster, tougher enemies. The 20 after ''that'' had even faster enemies and ''invisible walls''.
* In ''VideoGame/{{Tutankham}}'', after the fourth stage, the first four start repeating over and over again with more locked doors.
* In ''VideoGame/TheLegendOfZeldaSkywardSword'', the Skyview Temple has to be visited twice. In the second visit, more (as well as new) enemies are included, some new puzzles are added, and the last fight is against three Stalfos, offering a much trickier fight.
* [=E3M9=] "Warrens", the SecretLevel in ''VideoGame/{{DOOM}}'' Episode 3 starts out as completely identical to the episode's first level. Until you reach the [[YourPrincessIsInAnotherCastle "end"]] and hit the "level complete" teleporter, when the walls around you suddenly come down and you find yourself in a giant room with a Cyberdemon. And it [[FromBadToWorse only gets more insane from there...]]
* The first few rooms in Level 17 of ''{{Abuse}}'' appear to be identical to the tutorial level from the beginning of the game. Then it kicks your ass harder than any of the previous levels ([[NintendoHard and that's saying something]]) and opens up into a different, longer path than the original.
* ''VideoGame/TheSecretWorld'' is another offender. While the game areas don't repeat, and new enemies show up constantly, the dungeons follow this trope to a T. There are five ordinary dungeons in the game - Polaris, Hell Risen, The Darkness War, The Ankh, and Hell Fallen - at QL levels 3, 5, 6, 8, and 9 respectively. Then there are three elite QL 10 dungeons - The Facility, Hell Eternal, and the Slaughterhouse. However, there are five other elite dungeons which are nothing more than the first five dungeons with monsters brought up in power level on a strictly numeric basis - which actually makes them (relatively) easier given you are allegedly at QL 10 equipment when facing these dungeons. Worse still, after beating The Gatekeeper (who keeps weaker players out of Nightmare dungeons), the Nightmare dungeons are the elite dungeons all over again, though with the difficulty ramped up considerably further and the bosses gaining new tricks which actually makes them (mostly) dangerous, as well as cranking up the damage they deal considerably and putting a time limit on many bosses (after which point the bosses will rapidly kill you).
* In ''VideoGame/CallOfDuty 4: VideoGame/ModernWarfare'', "Heat" uses the same map as "Safehouse", but during the day, with different enemies and objectives. Also, most of the Special Ops missions in ''Modern Warfare 2'' are rehashes of singleplayer maps with either twice as many enemies or [[ImplacableMan a Juggernaut or two]] thrown into the mix.
* ''VideoGame/PN03'' recycles two of its levels, in addition to reusing room designs.
* Three of ''VideoGame/RainbowSix 3: Raven Shield'''s maps are revisited in the game's second half. The prequel ''Rogue Spear'' recycled a couple of levels as well, but for plot reasons.
* ''VideoGame/WonderBoy'' makes a science of recycling level designs. On top of that, every single boss stage has an identical layout, just with different enemies and power-up placements.
* In ''Andorogynus'' (a ShootEmUp by Creator/TelenetJapan), after playing through first six stages, you undergo a sex change operation and play through them all over again as a woman.
* ''VideoGame/MonsterHunter 3 Ultimate'':
** Several of the high-rank missions are about hunting PaletteSwap versions of previous monsters. These revamped opponents are far more aggressive, their attacks may be of a different element from the originals and, at the start, you're placed randomly in a part of the battlefield, far from the resting area, and the supplies to help you won't arrive until much later, when there's little time left to hunt the monsters.
** In addition to new monsters and subspecies of old monsters (described above), the old monsters themselves return as well with buffed HP and attack power. Even the Great Jaggi can cause trouble at first, and monsters like Gigginox and Lagiacrus become a nightmare because of this.
* Five of the later towers in ''VideoGame/PandorasTower'', namely from the sixth to the tenth, are thematically (and, to an extent, structurally) modeled after the first five towers. In fact, whereas the first towers give tribute to the gods of wood, earth, water, fire and metal, respectively, the subsequent five give tribute to the ''goddesses'' of those same elements. But as expected, the latter ones have tougher enemies and bosses, and some of the puzzles are more convoluted as well. The bosses are all different, however.
* In ''Frak!'' for the BBCMicro, after completing the third level, the levels repeat themselves with everything besides the status numbers vertically flipped.
* B Ghost House in ''VideoGame/{{Something}}'' is a remix of the first half of A Ghost House, but with black fog, Pidgit Bills, and no warning coins.
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