Arrow keys to move, if you're on the ground, down will make you crouch. If you're in mid-air, you will ground pound, and jump into a pit to die, no sound though.
Drumd Made the original, of course, Nintendo made NSMB, he just left death and ground pound animations sitting around without coding them in. The animations were kinda glitchy looking, I tried to fix it the best I could, but some visual glitches still linger. Feel free to add to it.