It often seems that, when it comes to mobile, in-app purchases and a plethora of tacky pop-up ads are the way most developers go about monetising their games. So it's refreshing to see one trusted to stand on its own two feet, with a one-off - and very reasonable - purchase price, after which players are left to get on immersing themselves in game play without any distracting should I/shouldn't I spending dilemmas.

Then again, many aspects of Ustwo's Monument Valley go against the prevailing wisdom, sometimes wonderfully so. It's short - perhaps too short - at only ten levels, and yet it seems like the perfect length, ending just as the ideas and inventiveness become a little repetitive. It's also deceptively simple; based on M.C Esher's famous impossible constructions drawings, buildings and pathways tilt and spin to guide a princess through a series of mazes and puzzles, each more elaborate and deceptive than the last.

There's nothing massively complex to grasp here, but it's a beautifully serene and immersive experience, fantastically rendered in a muted palette of pastels. The ingenuity and trickery behind the optical illusions and shifting blocks (at times you can spin the whole building around, revealing hitherto unseen solutions) are nothing short of breath taking, each level prompting thoughts about what could possibly come next. There's a soundtrack too, an atmospheric mix of quietly groaning buildings, a light breeze, and soft sitar picking mixed with the soft shuffling of your steps and the occasional bubbling stream.

If you've ever played Echochrome, you'll be at ease moving through Monument Valley, but there's plenty to enjoy here even for the novice gamer. It's a relaxing, languid thing of joy, an escape almost, far away from the garish, crash'n'bang flair so many mobile games wish to embrace.

You'll need to think, but it's pleasantly challenging, not infuriating, and subtle in the way in draws you in and keeps you mesmerised. £2.49 sounds a lot for an app, but this is a thing of beauty, and game you can return to time after time and still bask in its prettiness.

You can pick the game up on iOs by heading here. An Android version is "coming soon".