A game where you can build houses, decorate them, make people and control them. You can make them homosexual, you can make them kill themselves and you can make them fight.
The Sims has quite a range of expansion packs such as 'House Party', where you can order caterers, buy party outfits and all kinds of party accessories ranging from punch bowls to jacuzzis.
On 'The Sims Unleashed', you can buy pets.
Actually a good game, but it can get boring.