I know there was a thread about this while it was still in beta, but now that it's released I think it needs a new topic.
Cities XL is a city planning game very similar to the classic Sim City. Its unique aspects come from the multiplayer interaction, where different cities can trade resources for income in order to support ever growing populations. You can also visit other players' cities in 'avatar mode', where you can click on spots on the map and walk around. The game has a large selection of models and high quality textures, so even at maximum zoom the game doesn't look terrible.
Here are some screenshots I have of my 3.6 million person city:
http://www.xfire.com/screenshots/wecksyrex/The game is a bit pricey, at $50 for retail and $19 for a three month multiplayer subscription. On top of that, content is still being added in, and mass transit systems will not be implemented until the third content pack. There is also a pretty serious memleak problem that can cause crashes or just reduce frame rate to very low levels, so save often.
