Quartet

Quartet is played on a 4×4 board with a set of distinct pieces, each carrying several traits, tall or short, light or dark, round or square, hollow or solid. The catch: you don't choose your own piece. Your opponent hands you the piece you must place, and then you hand them theirs.

You win the instant any row, column, or diagonal is completed by four pieces that all share at least one trait, and it doesn't matter who placed them. That means you can win with a piece your opponent unwittingly gave you.

• Place the handed piece on any empty cell, then pick a piece from the pool to give your opponent.
• A line of four sharing any single trait (all tall, all hollow, etc.) wins immediately.
• If the board fills with no such line, the game is a draw.

• Desktop: click an empty cell to place the piece you were handed, then click a piece from the pool to give.
• Phone & tablet: tap a cell to place, then tap a pool piece to hand over, no keyboard needed.
• The piece you must place is shown above the board with its traits described.

• Vs Computer, choose Easy, Medium, or Hard.
• 2-Player, pass one device back and forth with a friend.
• Online, play a live match against a real person.
• Classic uses 16 pieces with four traits; the 5-Trait variant adds a fifth trait and 32 pieces.

• Before you give a piece, scan every open line, never hand over one that completes a shared-trait four.
• Watch all four traits at once; a line can be won on a trait you weren't tracking.
• Steer the board toward positions where every remaining piece you could give is safe.

This is Quarto, invented by the Swiss mathematician Blaise Muller and published by Gigamic: a 4×4 board, sixteen pieces each carrying four binary traits, and a line of four sharing any one trait wins.

Its famous rule is the one preserved here — you do not choose your own piece. Your opponent hands it to you.

That single rule is what makes the game unusual among abstract games. There is one shared set of pieces rather than a set each, so there is no "your material" and "mine"; every handover is both a move and a gift, and the hard part is finding a piece that gives away nothing.

Quartet reimagines the give-your-opponent-their-piece genre of trait-matching abstracts, where the hardest decision is which piece to surrender. This is an original, free browser version with three computer levels, pass-and-play, and live online matches, no download or sign-up.

A free, original browser game on PlayPendium. No download, no install.