Today's code defines 'fittest' as lifetime fucundity - bascially, the extant bot with the most extant descendents, which is a pretty good definition IMHO, but if people have a better definition, I'd be happy to hear it.
Perhaps what would be best is to add different kinds of canned 'best bot' queries so people can select the kind of 'best' they are most interested in I.e. oldest extant bot, extant bot with most nrg/body, one with the highest kills, most effecieint nrg usage, etc.
Over time, I want to add the ability to tie scripts or the equivalent into having externally defined fitness criteria so the human can breed bots towards a goal other than pure survival. For example, Elite's challenges have got me thinking that it would be cool to breed bots towards solving them. This would obviously provide objective criteria for what consitutes best.