Cross Fingers, the block-shifting puzzler from Mobigame, is currently free to download from the App Store - reduced from its usual price of 99c.

Over the course of a whopping 510 levels, Cross Fingers has you dragging blocks around the screen to complete ever-tougher tests of your spatial perception.

Cross Fingers also boasts an Arcade mode, which challenges you to rack up the highest score possible in a sort of puzzle-based Survival mode.

Whichever way you choose to play it, Cross Fingers is a very solid puzzle game.

Worthy of a very respectable 4/5, in fact.

You can grab Cross Fingers from the App Store for free right now. But, puzzle fans are advised to act fast - this is a limited-time deal.