Cut It is a level-based puzzle game from Petri Purho that harnesses a physics engine, block shapes, and a simple but novel mechanic; you cut things.
You click anywhere on the game screen; a scissors appears, you drag to indicate the line of the cut, and release. On-screen blocks are cut along the line, and typically begin to fall, sliding apart along the cut. Your objective is to get a white block to a green platform, which solves the level.
It's surprisingly difficult; the physics of blocks parting along a cutline is fairly difficult to predict, although you do learn some techniques over time, and the use of a physics engine prvents it from becoming as cut-and-dried as many puzzle styles.