Mega Man 8-Bit Deathmatch, the fan-made Doom mod, at least released on Friday. The FPS, stuffed full of Mega Man characters, weapons and other assorted sprites, is free. It is currently in alpha.Feel free to watch this gameplay video made by slyfox(who got me into playing this):
http://www.youtube.com/watch?v=LeMP_SsuUME&list=UUykq66gjwHrdSuSGt5PABeg&index=7&feature=plcp(this video will help you with setting up before playing.)
Here is the download page:http://cutstuff.net/mm8bdm/?page_id=5
IT ALSO HAS MULTIPLAYER!