Cogs brings an admirable variety to the standard sliding-tile type puzzles, and its much more than that.
Cogs is solely based on the age-old sliding-tile type puzzles, where you only get to move your tiles in only two dimensions, without having the freedom to lift them, unlike jigsaw puzzles.
As the name suggests, the game has a mechanical theme, the puzzles when solved result in a working mechanical contraption, and quite a satisfying one too! The various mechanical objects such as gas pipes, gears, bells and their combinations result in a wide variety of puzzles resulting in equally diverse machines.
The addition of 3rd dimension adds to the varied type of puzzles, even though the puzzles are 2-dimensional at any given instant.
Game-play:
The game, like any other, starts with the simplest of puzzles, a small array of tiles and a straight problem, and slowly grows in complexity with the addition of gears, combinations of pipes & gears, interconnecting them in 3 dimensions, two-sided puzzles, addition of musical notes keeps it interesting. The scoring system typically awards points for a working solution and bonus for beating target time or number of moves, as one could guess from the genre, thus unlocking more puzzles. The complexity of each puzzle's objective also grows gradually. The later stages especially require one to observe the setup, the resources available and solve the puzzle mentally before proceeding to make any actual moves.
Points may alternately be scored in the challenge mode, where one competes against time or has to solve in under a fixed number of moves.
Sound:
The background sound gets monotonous, repetitive after few continuous hours of game-play, though of course, for long hours of game-play, one would have to be immersed in it, in which case they would not bother about the background music. On the other hand, the more important sound effects of moving tiles, chiming bells, rotating gears, leaking gas are realistic.
Graphics:
Graphics are quite satisfying for the game's pace. Neither do they stand out as striking nor do they dampen the overall feel. The animations of mechanical things are again realistic and amazingly the contraptions actually do seem physically possible, which adds much to the satisfaction of solving each level, and the longing to solve the next one too!
Replay value:
As with any puzzle game, once solved, there's hardly anything more to it. In Cogs' case though the challenge to better personal best number of moves and times remain the only motivation to play the game again. This in fact is a rather discouraging aspect. When solving for the first time, the bonus targets seem totally unrealistic, they're basically meant for the second run when you know the solution and you mechanically have to achieve it.
Overall, having been based on the old-school concept, it brings enough variety and playing satisfaction. And priced at $10, its certainly worth a try, or to gift to a kid, a patient one though!