The "Minus World" in Super Mario Bros is one of gaming's most famous glitches, but what's actually happening as Mario slides through the wall at the end of World 1-2?
As YouTuber MagicScrumpy explains, the commonly-held theory that a missing warp zone pipe number is at fault is incorrect – the answer, it turns out, is a lot more complicated. MagicScrumpy illustrates the way Super Mario Bros' code works out which level to send you to as you drop down a warp zone pipe, and how swapping variable values creates the endlessly-looping Minus World.
Even if you're unfamiliar with hex editing and coding, this look into the inner workings of a classic game is pretty fascinating.
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