If you have never heard of Animal Crossing, shame on you it is a life simulation game for the Nintendo GameCube. At the start of the game, your character moves into a new home in a new town. You start out by working at the local store to pay off your mortgage. Once you pay it off, however, you are free to explore your town and play at your own pace. There is no real structure to the game, you simply engage in a number of activities. These include digging up fossils, buying furniture for your house, and (my favorite) catching fish.
If you enjoy casual or sandbox games, I highly recommend this game.