Darwinia and its multiplayer counterpart Multiwinia have been available on PC for a while now, garnering positive reviews for their unique art style, bizarre premise, and blend of action and strategy gameplay. They're finally making their way to Xbox Live Arcade as one package later this year and should be a welcome addition to the service. There really isn't anything like this on XBLA. Darwinia is hard to explain, but let me give it a shot.
You arrive in a Tron-like computer world and are told by a nerdy Dr. Sepulveda that you must herd these little green men called Darwinians to safety. Sort of a real-time strategy God game, you have various units you can create that perform different functions. Squads are your primary unit, of which you have direct control to move them around the environment and attack enemy viruses that will kill the Darwinians. While you can normally move the camera around freely, when controlling a Squad the right stick is used to fire so the camera will follow you automatically. The Darwinians aren't directly controlled, but if you promote one of them to an Officer they'll obey his orders. Using your units and Officers you must get the Darwinians to the goal on each map.

When destroyed, viruses leave behind DNA that can be harvested by Engineer units in order to produce more Darwinians. Your Engineers can also extract weapons like grenades from item boxes lying around the map and activate buildings so that you can utilize them.
From what we can tell, Darwinia is a pretty challenging game. Your specific objectives change from map to map and there isn't a lot of hand holding explaining how to complete them. Discovery leads to satisfaction, though.
Playing Darwinia gives you a sort of strange, uneasy feeling. Maybe it's the sparse environments; the menacing ambient noises; the cold electronica. Everything from the story to the audio to the visuals is weird and unique.
When playing Multiwinia, Darwinians are called Multiwinians and make up your entire army. They carry lasers and grenades and will open fire on any enemy Multiwinians they encounter. You can move a group of the green guys by holding down the A button and then pressing X where you want them to go, or you can create Officers just like in Darwinia. Multiwinians are birthed from spawn points, which are captured by moving your army close to them. Crates will randomly fall from the sky containing power-ups.
The multiplayer game types are Domination, King of the Hill, Capture the Statue, Rocket Racing, and Blitzkrieg.
Domination: Capture as many spawn points as possible before time runs out. Any team that doesn't own any spawn point for 30 seconds will be booted.
King of the Hill: For every hill you control you score one point per second.
Capture the Statue: Carry giant statues back to your score zone.
Rocket Race: Fuel your rocket by capturing solar panels, load Multiwinians onto it, launch, then protect it until it lands.
Blitzkrieg: Capture enemy flags
We don't provide the 'easy to program for' console that they [developers] want, because 'easy to program for' means that anybody will be able to take advantage of pretty much what the hardware can do, so the question is what do you do for the rest of the nine and half years? It's a learning process. - SCEI president Kaz Hirai
It's a virus where you buy it and you play it with your friends and they're like, "Oh my God that's so cool, I'm gonna go buy it." So you stop playing it after two months, but they buy it and they stop playing it after two months but they've showed it to someone else who then go out and buy it and so on. Everyone I know bought one and nobody turns it on. - Epic Games president Mike Capps
We have a real culture of thrift. The goal that I had in bringing a lot of the packaged goods folks into Activision about 10 years ago was to take all the fun out of making video games. - Activision CEO Bobby Kotick