I made a punchit-like game in high school by scanning in the face of a guy I really hated (as did most people, so it was quite popular on the school network). Basically you blew away at him with a shotgun and his face disintegrated. First you shoot out his eyes, his cheeks, his jaw, and then the top of his head, then his skull is fully revealed and you can shoot out his teeth and parts of his skull until a little peanut-brain on the end of his spine runs around the screen. After killing him you unlock minigun mode. There were three sequals, none of them punchitish.
well, not a punchit engine, more like double dragon/fist of fury (but you understood that, most of you anyway)
It doesnt have to be a engine, a tut will do just fine. I'll look for the one darksun did, thanks