> Zyps are small creatures with minds of their own. You can > create dozens of Zyps, then decide how each will act. (Will > it run away from the others? Follow them? Eat them for > lunch?) You can combine rules and actions to create very > complex behaviors.

http://sourceforge.net/projects/zyps

I’ve never delved this deep into vector math before, but it’s going pretty well so far. I’ve already got about a hundred of the little critters following each other around simultaneously. (And already they surprise me with unexpected behaviors. When I’m done it’s gonna be like they’re really alive.)