It's impressive how the basic themes of stacking and combining themes remain so fresh, but Unmechanical rarely feels like it's retreading territory. There are a few exceptions to the well-conceived standard, however, particularly with regard to puzzles requiring you to balance objects on each other (where the physics engine gets annoying), but by and large you'll find the puzzles enjoyable and clever.
The puzzle diversity is matched by varied, beautifully rendered levels ranging from dank tunnels to hellish magma caves. While there's little in the way of interaction with "living" things (that is, other characters), you'll appreciate the way the artists play with activity in the background and draw your eye to more than just the puzzle you're working on at a given time. Indeed, art often clues you in as to how best to handle a puzzle. Pictograms don't simply spell out answers, mind you; you must carefully observe visual cues.
One early puzzle, for example, requires you to restore power to a lever that has got a severed, live wire. Below the wire is a large pool of water that undulates when an object from the background falls into it. You can solve the puzzle by dropping more massive objects in it, displacing the water up over the live wire and creating a makeshift connection to restore the lever to functionality. Visuals in Unmechanical are more than just a pretty face.
Sometimes you need to break machines to solve puzzles, rather than repair them.
The rest of the game's features focus on minimalism. Controls are easy with either a gamepad or the keyboard, but all you can do is move or grab stuff anyway. Sound and music are unremarkable but competently handled throughout the game, and the story, such as it is, unfolds bit by bit in a way that keeps you interested if not enthusiastic.
Otherwise, there's not much to tell: Unmechanical is a fun and clever game that treads familiar ground. And yet it's thoughtful enough to inspire your intellect and draw you into its world. You may not miss it once you leave it behind, but Unmechanical is a pleasant puzzler that keeps you busy for the few hours that it lasts.