Corewars!
Corewars is a game of competing computer programs, each trying to force the other to crash. There are various classes of program: the imp, which just keeps on running and hopes that the other guy crashes himself; the dwarf, which drops little bombs throughout memory, hoping to land one on a running opponent; scanners, which look for the opponent, trying to find & kill him; vampires, which try to run another program’s code. Back in high school, I once had a (briefly) highly-rated vampire.