polyomino.io

polyomino.io is a free real-time multiplayer arena built around one of recreational mathematics' oldest toys: the polyomino, a shape made by joining unit squares edge to edge. Where Tetris hands you a fixed bag of seven pieces, polyomino.io lets every player build their own — square by square, in whatever order they collect food — so no two figures ever feel quite the same.

The same engine powers three very different modes. Tetromino is a multiplayer take on the classic, with a shared well and a familiar 1×/3×/6×/10× line-clear multiplier that makes greedy stacking deliciously risky. Pentomino is slower and stranger: a picture in the centre of the world fills in piece by piece as strangers' shapes lock in beside yours, with no chat and no team — just a shared image quietly being completed. Domino is the sprint of the three, a colour-matching race to chain a bridge from wall to wall before anyone else does.

No accounts, no ranks, no tutorial. A nickname, a mode, and you're in.