I Could Be Even Geekier

I haven't taken much interest in video games since Tempest (although there were those very fun few days in the mid-90's when all I did at work was play Myst).

This, however, could make a gamer out of me yet: create your own primitive life form, and take it all the way through evolution to interplanetary travel.  On a Mac, no less.  How can I resist that?