An insanely difficult Game Mod of Super Mario World, Kaizo Mario World (literally, "Hacked" or "Remodeled" Mario World; known as Yūjin Mario in Japan) is well known for being the Trope Codifier of the Platform Hell genre (well eclipsing the popularity of earlier examples such as Jinsei Owata no Daibouken and the then-unnamed Super Mario Forever), and for being the game that launched a lot of Let's Players' careers on YouTube.
The whole thing is rumored to have started as a simple Mario World hack made by a Japanese internet user to challenge their friend, and by some unknown stroke of luck, was found and LPed by a team of Something Awful LPers as 'Asshole Mario World', based off the difficulty. The popularity of these original playthroughs spread across the internet, causing a lot more people to play the game. The game is pretty much also responsible for the wave of "super difficult" Platform Hell Mario World hacks that have been released, including most on the trope page in question, and those designed specifically to be played by commentators on YouTube for the frustration of the player in question.
The original hack was followed by two sequels, Kaizo Mario World 2 and 3.
See also I Wanna Be the Guy.
This game provides examples of the following:
- Ascended Glitch: You'll have to pretty much know a bunch of glitches in the Super Mario World engine to get through this hack.
- Big Boo's Haunt: The ghost houses are a sadistic homage to the already frustrating and labyrinthine ones found in the original. The Big Boo boss is made ridiculously hard.
- Bizarre Puzzle Game: What this game really is to the uninitiated. A third of the game is figuring out how to get past certain parts of the level by using certain tricks or exploiting the physics engine.
- Bonus Boss: Arguably those at the end of the Special World.
- Brand Name Takeover: Thanks to this game, "Kaizo" is now fandom speak for any ridiculously hard SMW hack or any hard ROM hack in general; several other hacks have adopted the name Kaizo, such as Kaizo Mario Bros 3 and Kaizo Mario 64.
- Butt-Monkey: Luigi gets dogged even though he isn't directly the protagonist. Why is this relevant? At the end of Kaizo Mario World 3, the game shows the total number of deaths you got throughout the game. Get 200+ deaths? You are ranked as Luigi, who is worse than a water flea (100-199 deaths).
- Couch Gag: Each of the three games have variations on the opening Thwomp trap pictured above. The first game positions it so that you won't die unless you jump, the second game inverts this (you have to jump in the right spot to activate an invisible block that stops the Thwomp from hitting you), and the third game puts a pit below you (though, like the first game, the text box will pop up before you fall off the screen).
- Cranium Ride: Spin jumping on dangerous enemies to pass over spikes or the like. Taken even further in 3, where an entire level is centered around riding on top of a Mega Mole while avoiding the scrolling scenery.
- Darker and Edgier: Twice over to the original source material accompanied by Sequel Difficulty Spike. The first text box of the game says it all.
- Mata ano onna ka yo? Yare yare da ze. (That girl again? Give me a break.)
- The second game is even darker than the first.
- Developers' Foresight: The extreme difficulty of the game seems to be designed so that even with save states, you will rip not only all of the hair from your head, but from at least 40% of the rest of your body as well. The Start-Select exit code is removed for all three games, so you cannot go back a level and snag any power-ups or Yoshi.
- Everything Is Trying to Kill You: As with most Platform Hell games.
- Foreshadowing: In Kaizo Mario World 3, the beginning message includes the words in English "PROJECT -KILLING PEACH-". Guess who you face in the first castle.
- Game Mod: Obvious.
- Grimy Water: Gray water is death.
- Guide Dang It!: The sequel mixes it up a bit by having a level consist not of ridiculous deathtraps, but a convoluted, Rube Goldberg-esque series of actions required to access the end of the level. Taken Up to Eleven in the penultimate stage of Kaizo Mario World 3.
- Hailfire Peaks: Special World 4 combines The Lost Woods flavour with Big Boo's Haunt foes.
- Hard Levels, Easy Bosses: Compared to the hell that's come before, Invisible Bowser is relatively easy. Underwater Bowser is another cakewalk. Hammer-Throwing and Fireball-Spitting Bowser is far more difficult, though not as difficult as the hell you've been through.
- Helpful Mook: Accidentally Assisting flavor. See Cranium Ride.
- Instant-Win Condition: Subverted, especially with the Kaizo Trap. If you fall off a cliff to nothingness after finishing a level in Super Mario World, you will still die; the original game was just kind (or smart) enough to not put cliffs there. Kaizo, not so much.
- Kaizo Trap: The Trope Namer, of course. One infamous level requires you to trigger a P-Switch near the end of the course so that Mario doesn't fall into a pit of lava and kill himself during the victory scene.
- Leap of Faith: Required way, way, way too often.
- Luck-Based Mission:
- The first special stage requires the player to perform a leap of faith over (essentially) a Bottomless Pit and hope that a fish jumps up at the right place for them to bounce off and continue. There is no set pattern to how the fish appear at all, meaning the jump comes down to pure luck.
- Special world level 2. 100 seconds and, while possible, you should probably save scum, as Pokey moves in random directions and could waste time you need to beat the level in time.
- Nintendo Hard: The easy levels. The rest are Platform Hell.
- One-Hit-Point Wonder: Enforced; many passages are only big enough for the small one-hit Mario to pass.
- Oddball in the Series: The third game is the only one with custom palettes, custom graphics, custom sprites, and even custom music.
- Platform Hell: Most of the game, although taken to further and further degrees by imitators.
- Press Start to Game Over: The title screen opens with a Thwomp crushing Mario, and quite a few levels try to kill you a couple seconds after they start.
- Save Scumming: Beating this hack (and others of its ilk) "legitimately", without using emulator save states, is virtually unheard of.
- Has actually gotten more and more popular as the game has turned into a well-known speedrun, with many people now who have beaten the games without save states. In fact, one has even beaten the game deathless.
- Schmuck Bait: The last bonus level has a huge pile of blocks, a leaf stuck underneath it, and a finish line. Guess which is the Schmuck Bait.
- Sequel Difficulty Spike: The second game just increases the hellishness of the first one.
- Slippy-Slidey Ice World: Hope you have your ice sliding skills perfected, these games exploit the mechanic's difficulty for all its worth.
- Speedrun: Especially the Tool Assisted kind. Some imitators are actually made purely for Tool Assisted Speedruns.
- Spikes of Doom: As Munchers and normal spikes, and in great quantity in all levels.
- Temporary Platform: Used throughout the mod, including the infamous Kaizo Trap.
- Trial-and-Error Gameplay: You won't see many traps until you get killed by them. This is, again, one of the most common features of both the original and imitators.
- Video Game Remake: Kaizo Mario Advance 2. How shall the gameplay of Luigi from the GBA version work with these levels?
- Serial Escalation: How insanely difficult will this stage be? Practically gets turned into an art form.
- Shout-Out: The third level of the first game is called Cerulean Cave, a reference to a location in Pokémon.
- Yank the Dog's Chain: The reward for beating the Special World in the first game is a Feather, so you can actually avoid the One-Hit-Point Wonder rule... only it's stuck in a place that is impossible to escape, since the blocks are too high for Mario to jump over. You cannot exit the level by using Start-Select, either.