Spore is Will Wright's (Sim City, The Sims) new masterpiece. Spore starts a player out as a single-cell organism swimming around in a primordial soup.

As Will Wright explains it, this stage of the game is essentially like Pac-Man, and you basically devour microbes smaller than you while avoiding those that are larger.

You can upgrade your cell by adding cilia, flagella, and other defense mechanisms in order to gain any advantage possible for a single cell.

At this point, the gameplay switches from 2d to 3d but is still essentially the same: devouring the less fortunate and avoiding the bullies.