The video game Spore just came out. It was in development for years, the brain-child of Will Wright, the guy who did all the Sims games. Supposedly Wright got input from scientists while making the game, but the game is getting mixed reviews from scientists. Some are saying that it actually spreads misinformation about evolutionary processes.
Some of the criticism I've heard is that there's too much tinkering on the part of the user to have the dynamics qualify as anything resembling evolution. Another is that the game has pre-ordained directionality: There are five stages to the game, and they always occur (cell, creature, tribal, civilization, space). Evolution doesn't work this way.
If you want to try a free video game that's a little truer to evolutionary dynamics, here's NERO, Neuro-Evolving Robotic Operatives, developed at the University of Texas at Austin. It's a combat game in which you tune the selection pressure of evolving populations of robotic soldiers in order to develop armies with particular characteristics. For example, in training mode (pictured here), your robots spawn by falling out of the sky and landing in the arena.
You can place obstacles, such as walls, or enemies, such as machine gun turrets, anywhere in the arena. When soldiers die from being shot by enemies, new ones spawn, and the controllers of the offspring are mutated descendants of the other members of the population. You can control the behaviors selected for by adjusting scroll bars. For example, you can control whether your soldiers evolve to be "kamikazes" or "evaders" by adjusting the pressure for them to either run straight at, or avoid gun fire. Once you've trained an army, you cut them loose in a battle situation and see how they fare.
Their morphologies don't evolve, just their controllers, or "brains". And this is really more a case of artificial selection than natural selection. Natural selection is pressure from either external environmental conditions or interaction with other non-human organisms that causes differential survival in a populations. For example, if the environment cools in a particular region over multiple generations of a species that has fur, like a fox, those individuals with thicker fur might be more likely to survive and reproduce, and thus more offspring in the population will have thicker fur.
Artificial selection is when the selection pressure is determined by humans. For example, a farmer is able to sell plumper, sweeter corn at market, so each time he harvests and plants, he picks kernels from the plumpest, sweetest plants to start the next crop. After successive generations, corn in this population has much larger, sweeter kernels than it did several generations ago.
Video games are going to necessarily involve artificial selection. Otherwise, the player would have nothing to do. Evolution by natural selection is an inherently undirected process, and wouldn't much make for fun game play.
I've done some work with evolutionary algorithms, and I enjoy sitting back and watching a population evolve. But I don't think this has much wide appeal. And even though NERO is a cool concept, when I played it, I didn't really think it was all that fun.
Creatures is another game series that was developed in the 90's, but I never played it. There's something appealing about the idea of playing god, determining who lives and dies in an evolving ecosystem based on your decisions, but the interaction is indirect, and its the evolving organisms that are doing most of the work.
So as much as I think the idea is cool, I don't think video games really based on evolutionary processes are going to take the gaming world by storm. However, I think if they are faithful to the science, mini-games based on evolution could be invaluable teaching tools at just about any level in education.