Tetromino Tiling
There are five ways to join four squares edge to edge, counting rotations and flips as the same. Use them to fill each board — but some boards can never be filled. Can you see why?
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How to play
- Pick a piece, then tap the board to place it — or drag it there.
- Use Rotate and Flip to turn it. Tapping the held piece again also rotates it.
- Tap a placed piece to pick it up, or drag it somewhere else.
- With a keyboard: focus the board, move with the arrow keys, R rotates, F flips, Enter places.
- Depending on your screen, the board may be shown turned on its side — it’s the same puzzle.
Learn more
Tile the board with four-square pieces. Try the rectangle challenge, then explore the checkerboard to discover why it behaves differently. The search uses backtracking and can use two copies of each shape.