BBC Worldwide has Doctor Who: The Mazes of Time (iTunes Link) for the iPhone and iPod Touch and Doctor Who: The Mazes of Time HD (iTunes Link) for the iPad in the iTunes App Store for FREE (regularly 99-cents) for a limited time.

For the first time on iPhone and iPod, enter the world of Doctor Who in a brand new action puzzle adventure!
An intrepid traveller through time and space and the last of the powerful Time Lords, the Doctor is armed only with his incredible intelligence and his sonic screwdriver. Join him and his human companion, Amy Pond, as they race to save an innocent family attacked by a rogue Dalek and hurtled into the depths of history. Your journey will take you from ancient Incan temples, to the frozen tombs of Telos and a stunning finale on a Dalek ship. Defeat your favourite enemies, solve devious puzzles, and restore peace throughout time!