Free game: Puzzle Retreat - Earlier this year, The Voxel Agents released Puzzle Retreat. The game proceeded to rule our mobile devices with an iron fist, attracting our attention more than any other game. And for good reason, too: it's one of the most polished and entertaining puzzle games out there! To celebrate its awesomeness, Puzzle Retreat is currently free for iOS devices. The sale could end at any moment now, though, so be quick!
Free game: Apple Bin - Sometimes you just wanna throw some apples around. Apple Bin from Ruxar is a physics puzzle game that gives you a cannon full of apples and challenges you to do all sorts of stuff with them. Well, mainly get them in the bin using as few shots as possible, but in order to reach the bin you've got to avoid dangerous things and move some junk out of the way. Like giant concrete boulders, wooden planks, sawblades, portals, crates, gravity inversions, etc. It's a simple idea with a great implementation, and it's completely free from in-app purchases and all that other rubbish many mobile games like to feature. Just plain old apple-based puzzle solving! (Android / Windows Phone)
Almost free: Fish Puncher - Guess what this game's about? The official description says it best: "In a near-future dystopia, psychotic demon fish have enslaved humanity (for some reason or another - Global warming, probably). It's up to you, the Fish Puncher, to liberate us all in a convenient, two-minute burst of frantic arcade-style action. Punch stuff, punch more stuff, get a high score, be a hero." (Android)