SPORE 

Spore is an innovative Sim-like video game that allows you to create a race. The game is available for many platforms, including Windows and Mac OS X, so it should appeal to anyone. The game allows you to create a single-cell organism that will evolve throughout the game. The goal of the game is supposedly to get to the space. That goal will be difficult if your race can't develop intelligence and a sense of investigation. Thus, every choice that you make from the get-go will influence the outcome of your race. For example, if you make your organism a vegetarian, it will be a passive organism, if you make it a carnivore, it will be aggressive. All the small details count. It is really fun seeing how a little cell can become an animal, and then develop skills like building fires and things of the sort. The graphics also help a lot in visualizing all the detail put into the gameplay. Of course, you need to be careful not to get eaten by other organisms before you can defend yourself. You don't ever want to be the pray.