Braid by Jonathan Blow and Number None
One of the best XBLA games ever to be released on the Xbox platform, Braid is a platformer with much more depth than your average game. At the heart of the game, Braid is a puzzler with elements of platforming but adds a unique design layer that allows players to control the flow of time.
When your beloved princess is abducted, you venture into unique worlds through portals located in a house, to try and save her. As each new world is unlocked, so to does new mechanisms to manipulation time. For example, the player has the ability to rewind, slow objects down and live parallel realities. Across the game, players will not see one piece of filler content as each world provides new game play mechanics, art and enemies.
If you are hesitant to start playing indie games, Braid is a great starting point. It has challenging gameplay, dazzling art and creative puzzles that is expected from any AAA title. Jonathan Blow and Number None are currently working on their follow up game called The Witness.