I'll be honest I rarely play anything on Xbox LIVE Arcade, nothing peeks my interest.  However I heard about LIMBO a few months ago and saw concept art and screenshots and was very intrigued.  Got my copy a few days ago and I just couldn't put it down.  

'll be honest though, the game is creepy. One specific example would be when you had to cross a specific body of water that had no ledges or anything to jump on. At that point you see a person walking towards you and they walk right into the water and drown. You can now cross that body of water since they are floating on the top. Spiders, faceless enemies, and dark dense landscapes all add to the creepiness factor. I read in another review a few days ago that you should play alone in the dark. Turn off Xbox notifications and play.

If you're on the fence about this title, or you're just not sure, Go read my LIMBO Review.