Basically, Limbo is the platformer version of Portal, but instead of an Apple-based facility with the female HAL-9000, this story is about a boy trying to get his sister back from a world of obscurity which also lacks all colors but black and white. The main character (named Boy by the credits) is shadowed out, much like the other characters and features in the game. The only differently colored part of his body is his eyes, which are like a flashlight of sorts in the case of walking in front of another black object. He starts his journey by going to the right, and pretty much travels that way for the rest of the game, as is the custom in the country of platformers.
During the game, you will encounter numerous traps and often have to sit for a moment and make your plan of attack, because the developers really made the puzzles appear as something they're not. An early box/water puzzle is proof of this (had me stumped for about 20 minutes until I realized what you were really supposed to do). The physics engine allows for water and gravity based puzzles as well, so watch out for those, as Boy can't swim and doesn't have springs on his legs.
It's 1200 MS Points and came out today, July 21st, so I suggest the few of you with Live go download it and check it out. It's worth the $15.
Trailer: http://www.youtube.com/watch?v=bV-0w8I-oAc
