Braid poses a time-traveler's dilemma, what if you could go back and undo all your mistakes? In this side-scrolling world, you can. Biffed the timing on jumping those koopas? Back up in time and get it right the next time. Oh, but it's not that easy -- some things aren't affected by your time travel. It makes for mind-warpingly interesting puzzles that involve overlapping, but not concurrent, time lines going in different directions. Weird and wonderful!