The most ambitious gaming idea comes from the man who created the Sims. Spores is a game where you assemble, design, and name your own species from hundreds of different options, but that's just the beginning. To the left is what I created. The paint job is screwed up, but he is a Derfus. You can download the creature creator for free from the games website. Here's the description from Yahoo.
First, it's Pac-Man, starting you off in a drop of water as a single-celled organism simply eating to stay alive. Provided you do, you'll grow into a comically alien creature and romp around the planet in a 3D action game. Eventually you'll meet and mate with others of your kind, forming a tribal society that will interact diplomatically, militarily, and even religiously with other tribes on the planet. And over time, you'll develop the ability to blast off the rock and travel the galaxy, scouring thousands of other planets as a trader, conqueror or explorer.