Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
PainTown is a 2D fighting game somewhat similar with popular titles like Street Fighter (it even allows you to play with a character called Blanka), with versions available for Linux too, besides Windows and Mac. The nice thing about PainTown is that it runs natively on Linux and it's a standalone game, so you won't need any emulator like NeoGeo to play it.
PainTown 3.2 in Debian
PainTown is completely open-source and offers a source tarball on their official SourceForge.net website.
PainTown is just great for its gaming type, it allows to be run in fullscreen (using paintown -w switch) or in window mode, it supports high resolutions, including 1280x1024, and comes with default background music.