MUGEN is a free fighting game engine that allows people to plug in their favourite characters and have them battle it out against each other. Computer-controlled fighting game fighters against other computer-controlled fighting game fighters in an endless loop. I came across saltybet.com by chance, in a climate when fighting games are all about balance and skills it is refreshing to see such a thriving scene of pure unadulterated silliness. The interesting thing is the pure diversity of characters that are available on the roster, you can have Toejam fighting against Ryu from Streetfighter, Dr Doom against Goldie from Primal Rage and so on... the range of characters and the diversity of the games they come from is mindboggling! There's even an Edvard Munch character inspired by 'The Scream'... you have to check this website out, it is amazing!
I've linked to a video where you can truly watch the horribly unbalanced and buggy matches.