Gray Sky Games
An implementation of the popular Sokoban puzzle game. The goal is to push the crates onto the designated squares without getting stuck.
Great educational value for kids or non-kids. Reasonably attractive graphics (except for the odd-looking blue hero), we rate 4 out of 5. Features include multiple undo, mouse controls with auto-path-finding, many levels included, and you can add your own levels. Sugar-free. Recommended by more dentists. Free and open source.
A small game for Windows and Mac OS X based on Tetris. Features include smooth animation, and carefully fine-tuned movement controls. May be habit-forming. Free but not open source.