M.U.G.E.N is a freeware 2D fighting game engine developed by Elecbyte, originally released in 1999. It became a legendary part of internet culture because it allows users to create and import their own characters, stages, and UI elements, leading to a surreal and chaotic ecosystem where Homer Simpson can fight Ryu or Ronald McDonald. The meme culture surrounding M.U.G.E.N focuses on the 'broken' nature of fan-made characters, the hilarity of impossible crossovers, and the high-stakes gambling of SaltyBet. Today, it remains a symbol of pure internet creativity, representing the absolute peak of crossover madness and the 'anything goes' spirit of the gaming community.