Here's a delicious little treat from DJ Trousdale at deviantART. Crossblock is a simple and rewarding puzzle game with a sublimely deceptive difficulty curve. At first, you might think it's too easy—after all, each puzzle is just a collection of white squares on a grid—but the complexity grows organically, quicksanding you deeper with each level, until you find yourself waist-deep in Puzzle Solving Mode, goggling at some mad conglomeration of blockwork, your brain shutting down in whinnying, eye-rolling stupefaction.
Your goal is to eliminate all the blocks on a level by dragging a line across them, one horizontal or vertical group at a time. Each level has a number that indicates how many blocks you can cross out at once. Just click and drag across a group, consisting of exactly that number of blocks, to erase them.
This is all a lot easier to understand when you're looking at it, and the game eases you into it with a gracious and sinister hand. The lovely hand-pixeled scrolling backgrounds and jazzy soundtrack (all by the game's author) help make you feel comfortable and unthreatened, but don't be fooled. There will come a point where you just can't believe that such a straightforward, honest-looking pile of blocks can hold so many baffling complications; that such a friendly, casual game can so effortlessly grab you by the peaknuckles and lead you around the room skipping.
Nice work, DJ Trousdale. Good puzzle game.