Singleton traffic

• Tiles can't move horizontally if there's something vertically adjacent to them.
• Tiles can't move vertically if there's something horizontally adjacent to them.
• You win when you can't move (because all the tiles are stuck)

Use the arrow keys or WASD to move in a direction. Press Z to undo your last move, and R to restart the current level.

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This is an experiment to see how a game can work with only one noun. A single repeated element with simple rules of behaviour can be player avatar, wall, and puzzle piece all at once. Despite this, the puzzles are complex enough that most of them can be solved in several ways.