polyomino.io — multiplayer FFA, Pentomino, Domino & Triomino in your browser
polyomino.io is a free, browser-based, real-time multiplayer game built around the classic shapes of recreational mathematics. You start as a single coloured square, drift through a shared arena, eat food that matches your colour, and grow into a 2-, 3-, 4-, or 5-cell polyomino — then dock the finished figure onto the playfield to score. No accounts, no downloads, no install: pick a nickname and you're in the next round.
Four modes, one engine
Every mode in polyomino.io shares the same primitive — drift around a 2D arena, collect coloured food, dock the figure you've built — but each one wraps those verbs in a different objective. You can switch between them at the start screen by tapping the Mode card.
Tetromino
The headline free-for-all: a real-time land grab on a shared square arena. You spawn on a small solid block of your own colour — your home territory — then grow it by collecting matching food, building four-cell tetrominoes, and docking each finished figure back onto your own block. Only tiles you dock through play count toward your share of the arena, so every trip home matters. Attack in two ways: fly a finished figure straight into a rival's block to vaporize it for a ram bonus, or fire a recoil shot to chip an enemy tile off one mino at a time. Wedge your territory flush against a neighbour's to fence them in and wipe them off the board. The first player to blanket a quarter of the arena with their colour takes the round.
Pentomino
A cooperative picture-filling mode. Each room is built around a single image — a heart, a star, fan art, an OWL skyline — drawn faintly in the centre of the world. Players grow into five-cell pentominoes and drop them onto the image; cells that match the picture's colour at that spot lock in for 10 points each. The player who places the last cell of a completed picture earns a 100-point completion bonus, and a fresh picture takes its place. Pentomino rewards a calm aim over fast hands.
Domino
A short, tactical bridge-building race on a 100 × 100 board. The cyan left wall and the orange right wall are dockable in their own colours, and the round ends the instant a chain of docked stones spans the gap from cyan to orange. The player who places the closing stone earns the win bonus — even if other players built most of the chain — so endgame positioning is where rounds are actually won and lost.
Triomino
A collect-and-deliver mode. Every player gets a personal 4 × 4 drop zone — tagged with your name and colour — dropped at a random spot on the board. You grow a three-cell figure from food of any colour, then carry it home and drop it inside your own zone for a flat 30-point reward before heading back out for more. No colour matching, no rail docking — just route planning, and dodging rival figures on the way home.
What is a polyomino?
A polyomino is a shape made by joining unit squares edge-to-edge. The smallest ones have their own names: a domino (2 squares), a tromino (3), a tetromino (4), and a pentomino (5). The American mathematician Solomon W. Golomb introduced the term in 1953 and explored them in his 1965 book Polyominoes: Puzzles, Patterns, Problems, and Packings. The seven distinct tetrominoes are the falling pieces in Alexey Pajitnov's Tetris (1984); the twelve free pentominoes have been a fixture of paper-and-pencil puzzle design for the better part of a century.
In polyomino.io your figure literally is one of these shapes. You collect food square by square, and the order you pick the pieces up in determines what you end up holding. Two players spawning at the same time almost never end up with the same shape — which means the next move you have to make is rarely the same as anyone else's. Where most polyomino puzzles online are static (arrange a fixed set of pieces inside a fixed outline), polyomino.io runs the whole thing as a real-time arena: pieces move, collide, and die while you're solving the puzzle.
Controls in 30 seconds
- Move: your figure follows the mouse on desktop, or a touch-and-drag joystick on mobile. Pull the cursor in to glide; push it out to sprint. There is no "stop" — you always drift in the last chosen direction.
- Shoot / drop: left click on desktop, the round button on mobile. In Tetromino this fires a recoil shot (your rear cell flies off as a projectile and costs you a mino) — hit a rival to knock a mino off them, or a rival's block to chip a tile off it. In Pentomino this drops your finished figure onto the picture. Domino has no shooting — docking is automatic on contact.
- Rotate: right click on desktop, the curved-arrow button on mobile. Spins the whole figure 90° clockwise. Useful in FFA for shaping your block and in Pentomino for lining your shape up with the next missing picture slot.
The full guide — controls, rules, scoring tables, and per-mode tips — lives at How to play.
Why play polyomino.io?
- No account, no install. The game runs entirely in your browser. Type a nickname, pick a mode, and you're in.
- One playfield, four games. Every mode runs on the same engine and the same visual language of coloured squares, so picking up a new mode takes a minute, not an hour.
- Real-time, not turn-based. You're solving a packing or tiling problem while other players are crashing into your figure, taking your colours, and racing you to the completion bonus.
- Private rooms with friends. Arena mode is a private lobby where the host picks the game and rule set — Respawn (casual) or Hardcore (one life, last player standing). Share a pin code and play.
- Light and dark themes. Toggle with the sun/moon button in the top-right corner; your choice is remembered for next time.