Arcs 

Arcs is a radial puzzle game with rotating and sliding pieces. As in standard digital sliding puzzles, there is a piece missing, which is automatically filled in at the conclusion of the puzzle. To solve the puzzle, one must create the goal pattern of colors by moving its constituent pieces, via rotation of the rings and via movement of the arc pieces inward and outward using the empty slot.

To make things easier, most of the puzzles have redundant pieces, i.e. any piece of the same color will do just as well to fill a given space. Pieces are also randomly arranged at the beginning of each level (presumably in a way that is solvable), so a reset may ease the pain of a particularly confounding configuration.

While the simplicity of the game can be appealing in and of itself, several important features are lacking. There is no ability to save one's progress even on the longest of puzzles. The game is not at all playable for those with even mild colorblindness. And I found the game's sound effects to be irritating. With these flaws, Arcs tends to seem more like a successful experiment in game design than a full-fledged app.

Sam's Protip: Similar to solving a Rubik's cube, the puzzles are best solved one outer or inner ring at a time. This way the puzzle becomes (ideally) progressively less complex.