At just about every turn, Braid thumbs its nose at your expectations.

To hear one describe it, you'd think that it's all been done before, but the approach in this 2-D platformer title is fresh and new. The player journeys through a series of five worlds in Braid, collecting puzzle pieces along the way. The platforming sequences pay homage to everyone's inspiration, Super Mario Bros. — right down to a creature coming out of the castle at the end and proclaiming, "I'm sorry, but the Princess is in another castle." As expected, various enemies, ladders, locked doors, and harrowing jumping sequences try to obstruct your progress from point A to point B.

You don't need to have all of the puzzle pieces to finish a world, but you will need all of them to complete the game. You won't be able to reach some of the puzzle pieces until you unlock new abilities near the end of Braid. At that point, you can revisit the appropriate worlds with your new-found skills to obtain the previously unreachable items. The level selection screen helpfully displays the number of puzzle pieces that still remain in each world, so you don't have to needlessly revisit any locales.

Time behaves differently in each world, and you'll have to exercise your noggin to understand how time is moving so that you can figure out how you'll need to manipulate it to accomplish your goals. You may shrug this off as having been done in Prince of Persia, but after some reflection, you'll admit that the time-reversal mechanic in PoP is optional and is merely a way of fixing your mistakes, whereas time manipulation is vital to each of Braid's worlds. Time may flow normally in one world, whereas another world has time moving forward when you go to the right and backward when you go to the left.

Braid's artwork is in a watercolor-layered art style, which imparts the aura of a simple juvenile game. It actually has some difficult puzzles, so you'll have to attempt the same one many times — Xbox Live Arcade's Scott Austin bandied around the word "hundreds" — but it's a very forgiving title so you'll never die. To rewind time, you hold down the X button until you arrive at a point where you're still breathing.

Although we didn't receive many details about the plot, we were assured that Braid has a very compelling metastory about making mistakes, learning from them, and forgiveness. The surprise ending will have a twist, and we were informed that there will be extra worlds once you've completed the game.

If you're of the opinion that video games have been dumbed down recently to accommodate the lowest common denominator, then Braid, with worlds where you'll need to fully understand the time mechanic before you can act appropriately, may be just what the doctor ordered. The difficulty level may be punishing, but the game provides a very forgiving rewind mechanic so that you'll never die. It's this combination that will keep you attempting the puzzles again and again and again. Prepare to be challenged this fall.