CRE, which stands for Corewars Redcode Evolver, is an open-source program that
automatically generates programs for the game Corewars by using Charles
Darwin's theories on natural selection. When you start CRE, here's what
happens:

1. A population of warriors is created by randomly selecting instructions.
2. Each warrior's fitness is tested by battling with other warriors in the
   population.
3. The fittest warriors reproduce and replace less fit warriors.
4. The previous two steps are repeated indefinitely.

WWW: http://cre.sourceforge.net/