IWTBTG or I wanna be the guy, is probably the hardest game ever, even on medium. you only have 1 hp and so much as falling too far will kill you. platforms will explode, spike walls will come at you from nowhere, and it gets so insanely fustrating but some people are good enough to beat it.

IWBTG! A Very Hard Game About a Boy and 8-bit Masochism!