RoboBlitz is a unique addition to the XBL library.
Anyway, the gameplay takes a bit to get used to; the idea of controlling a rolling robot (that obeys the laws of physics) is somewhat unconventional. However, when you're familiar with the mobility (dashes/jumps), the game is pretty smooth. The puzzle can be tricky sometimes, but it's just a matter of careful exploration and observation. In addition, there is an option to use a Hint-system that keeps you on track. The game has two difficulties, so it won't just sit there after you're done for the first time. Graphics are awesome for an XBL arcade game, it even looks better than some Wii games (no offense).
The sound is descent with nice techno tracks and competent SFX. The game is more for those who have from 30 minutes to an hour at least of spare time, because that's how long it may take in order to beat each stage/level for the first time.
Oh, and the use of physics... is just beautiful. You can grab boxes, barrels, and bigger objects and use them to solve puzzles, and as weapons as well. You also get to upgrade your arsenal, so your character evolves along with you.
Too bad the game has no multiplayer so I don't believe you will come back for as long as other XBL games (Uno, Zuma, Mortal Kombat, etc). You will probably be done with it in 20 hours. I thought $15 was a little pricy at first but the production values do more than meet the expectations.
Oh, and it is powered by the Unreal Engine.