Bought Age of Booty
from XBox Live marketplace for 800 points. A demo also exists of course. It was released just some weeks ago.
It is a fun realtime pirate game. Very easy to learn. The singleplayer isn't anything else than a bunch of different maps, where you have an objective to reach to beat the map. Some maps where you team up with AI players are really hard due to your own AI teammates being extremely sucky most of the time. Haven't tested multiplayer yet, according to reviews the game is best as multiplayer.
Here is a review on IGN: