I think if this footage of Species: Artificial Life, Real Evolution shows anything, it's that gamers should not be allowed anywhere near a first-contact situation. What happens in this sandbox natural selection sim, where you watch species evolve rapidly as they deal with the changes in the climate and food chain, is just a little bit genocidey. Everything is going fine: the creatures crawl from the ooze that they once called home, they scamper over the world, they get a bit too numerous so an ice-age is set in motion for a little bit of population control, then the developer sets a deathbot loose. The selection gets a little bit unnatural at that point.
The Galapagos as a design document is a fun idea. There are a huge amount of variables to play with: the climate, the water level, the fertility. Then there's more unnatural enhancements, with you directly affecting the creatures mating habits, or physically plucking one from the ground to place elsewhere on the little island. Any physical stat you can think of can be exposed in the game engine: want to know a particular creature's neck width? There's a toggle for that. And global extinction is just a few toggles away. In this instance, the rover the developer sets loose kills all the low-strength creatures and feeds the high-strenth ones, but then they get reliant on the rover's lunch runs. So when he takes the rover away, the entire civilisation collapses.
There's not a lot of game yet, but that's coming. The simulation is what matters first and foremost, but when that's settled there will be species vs species fights to the death, terraforming, and fossil hunting.
The alpha builds will be free forever, but you can buy-in to the latest versions.