One of the biggest challenges in designing a game for a touch device is coming up with a way for the game to be played that feels natural. Platformers have toyed with free-running in the past and some like Canabalt have been immensely successful. Like others before them, Donut Games has taken free-running and made their excellent puzzle platormer Rat on the Run.

The gameplay is entirely uncomplicated by pointless controls and only requires touching the screen to start moving and to jump. Your jump's height is based off how long you press down, giving you a lot of finesse. Stop signs littered through levels provide you with an opportunity to consider your next sequence of jumps or even change your direction if needed.

Like other products from Donut Games much of the interface and character design is similar, but their clean menu and artwork is perfect for the iPhone. Other than the current 25 Challenge levels there's an Arcade mode for high score runs and a Canabalt-esque "Rat on a Scooter" bonus game to enjoy.

With the puzzles ranging from clever to outright diabolical Rat on the Run will keep you entertained for a while. It's all too easy to run out of the current content, but anyone after a great platformer or casual challenge, this is hard to beat.