LIMBO is one of the best Xbox Live Arcade games out to date.

User Rating: 9 | LIMBO X360
If you love challenging but simple puzzles then you'll have a lot of fun with this outstanding game. The controls are very simple, with one button to jump and the other to grab/push. However, the game can get very complex at times with many things thrown at you at once. One second, you'll be under mind control and can only walk a certain direction while dodging many obstacles. Next, you'll be chased by a giant spider jumping and ducking under spikes. Sometimes, you'll have to figure out where certain blocks go, walk upside down, and just pray gravity takes you where you have to go without getting smashed.
The game is ONLY! 1200 Microsoft points. You would be crazy not to buy it at that price. The only thing i can complain about is the story. It ends really abruptly and to be honest, without reading the description of the game you probably wouldn't even know you're looking for someone the whole time. But DON'T let that scare you. I promise, this game is more than worth the 15$.