Crack.com public domain release of Abuse.
Abuse is an arcade quality game running in a colorful 320x200 screen.
Abuse needs a 8 bits visual, so you might need to reconfigure your X server.

Here's the plot :

"Falsely accused and imprisoned in a high-security facility, you watch in
horror as a mysterious biogenetic experiment turns everybody around you --
guards and prisoners alike, into ravening, inhuman monsters.  Your only
hope -- steal a suit of powered armor, any weapons you can get your hands
on, and make your way to the deepest level of the prison, before the
plague spreads to the outside world." 
