Enthusiasts of the 1990 Nintendo video game Super Mario World modified the game's assets to create levels incredibly difficult to play. One release of three such modifications, Kaizo Mario World, associated the Japanese word kaizō (改造) for "remodel" with this genre of gameplay. These platforming games are designed to test the player's patience and skill while incorporating elements of mischief and discovery. For example, a Kaizo game might require the player's character to perform precise, technical jumps to cross a large gap only to hit an invisible block near the gap's end that sends the player-character to its death, making the player restart the level. The original Kaizo game was also known as "Asshole Mario".
Since Kaizo games are custom releases, they were traditionally played in video game emulators or cartridges that let users load their own games. Creators and fans of Kaizo games developed into a "scene" that expanded with the release of Super Mario Maker, a 2015 video game that let players easily create custom levels for each other without modifying another game's code. Members of the Kaizo community play, rate, and compare games for discussion on Discord, YouTube, and Twitch. They are often entertaining to watch simply for their intense difficulty. Some games feature in-jokes to the community. Kotaku described the community as "friendly, competitive, and creative" with famous players alongside new players.
Two notable Kaizo creators are PangaeaPanga and GrandPooBear, who also speedrun and livestream games in the genre. Noteworthy games within the genre include Grand Poo World, Quickie World, Super Dram World, Super Panga World, Invictus, and Kaizo Mario trilogy. Kaizo games have also featured at Games Done Quick speedrun marathons.
This scene continued with the release of Mario Maker's sequel in 2019; one notable creation took World 1-1 from Super Mario Bros. (1985) and added "dozens of twirling fire bars", making the level nearly impossible.
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