You don't want an RPG. Those take over your life to the point where you raise your hand to cast a fireball spell and then realize you're at work.

This is a couple of years old but is still the best FPS I've ever played (and I played Half Life 2) - Far Cry

I second the "any Civilization" too. I liked Civ3 the best (simpler but more action, bigger empires), but Civ4 is a quality game too (cool details but more complex and managing a huge empire is much more difficult than anyone venturing out of his basement should attempt).