A prototype build of Super Mario World has been shared online, showing us what the game looked like ten months before it launched in the US. The 1990 prototype was created during international localisation efforts, and shows a few changes between the early builds and the final version of the game.
The prototype was shared by Nintendo preservation site Forest of Illusion, who estimates that this was one of the first builds made for what would eventually become the North American release of Super Mario World. The findings have been shared in a YouTube video, and the game itself can be downloaded on the Forest of Illusion website for free.
Some of the more noticeable changes can be found in the game's script, as the prototype text includes grammatical errors, and even some unused content. For example, the two Boo characters are named "Boo" Diddly and "Boo" Jackson - both celebrity references that were dropped for unknown reasons. Bizarrely, as Forest of Illusion highlights, Boo Diddly was actually used in a previous game, making it more strange that this was changed midway through localisation.
Not everything in the prototype is in a completed state, but that's what makes it worth diving into. Throughout the playthrough, Forrest of Illusion finds incomplete levels, and others used for testing. Usually, these would be completely inaccessible to the player.
While you may be put off by the thought of playing through a less polished version of Super Mario World, you may find the numerous debug features appealing. Since the prototype was presumably made for testing purposes, you're able to play any level you want from the very start, and can even select which power-up you want at any given time. Also, if you're finding a level particularly irritating, you can just make Mario fly to wherever you want - or skip the level entirely. The game will still act like it was completed if you quit.
Check out the rest of the video for more details on the prototype, and maybe even dive into it yourself if you have some time to kill this Christmas Eve. Too often, little nuggets of gaming history will be lost to time, so it's nice to see this prototype preserved for all to appreciate.