Core Wars

n. A game between `assembler' programs in a simulated machine, where the objective is to kill your opponent's program by overwriting it. Popularized by A. K. Dewdney's column in "Scientific American" magazine, this was actually devised by Victor Vyssotsky, Robert Morris Sr., and Dennis Ritchie in the early 1960s (their original game was called `Darwin' and ran on a PDP-1 at Bell Labs). See core.