A Delicious Puzzle
For a sweet mental morsel, try the Chocolate Castle demo--it's part maze and part sliding-tile puzzle. You clear Easy, Medium and Hard versions of each of four rooms by shifting, joining, and eating pieces of chocolate. Four characters eat chocolate that's colour-coded to match them, but each disappears after eating one piece. The trick is to meld chunks of chocolate in advance, and timing is crucial: once joined, pieces can't be separated, so they can become roadblocks. The full version's 120 puzzles include twists like slippery ice and exploding Turkish delight.
The Hard-level puzzles may make you grateful to the makers for providing Undo and Redo buttons. If you're stumped, you can generate text files that record incomplete games to your Clipboard in chess-like notation. From there you can e-mail them or post them to the free BBS maintained by the creator, Lexaloffle Games, to seek help (or conversation) from other players. Chocolate Castle's charmingly retro music and graphics help this sweet stuff preserve a tiny 235KB footprint. Chocolate Castle, free 12-puzzle demo, $US20 for full (120-puzzle) game.