Of the eight billion Tetris ports and clones that have been released since the original, few are willing to mess about with the fundamentals—after all, they work remarkably well. You move a chunky shape as it falls, you rotate it so it better fits in with its blocky friends. It's a genius idea. And Stephen Lavelle has just twisted the core of it, in a very fun way.

Tetromino Slide is Tetris, but slightly bigger horizontally, and that's enough to throw you off your puzzling game. It's set on a typical Tetris playing field, but where there's an extra column present, to the left or right of the stack of tetrominos falling dutifully from the sky. This gap can't be filled as such, but when you tap A on your keyboard, the entire stack of tetrominos will slide to the left of the screen. And when you tap D, the stack will slide to the right. However, the pieces won't stay in their original formations: they'll also shift left or right, carrying on until they hit another tetromino, or a wall.

To help your brain adjust to Wrong Tetris, Lavelle has changed the other rules somewhat. Firstly, you initiate each block drop (meaning they won't fall of their own accord here), and secondly, you now need to clear four rows simultaneously to win the game. It's tough. I'm not very good at—but then I'm not much of a Tetriser. If you are, then you should know that Tetromino Slide has reshaped—in a maddening and majestic way—the classic game. (Via Warp Door.)