Quarto

A sharp abstract strategy game on a 4×4 board with 16 unique pieces. The twist: you don't choose your own piece — your opponent hands it to you. Line up four pieces that share any one trait to win, and build the longest streak against the AI.

How to play

Each of the 16 pieces has four traits: tall or short, light or dark, round or square, and solid or hollow. Every piece is unique.

You never pick your own piece — the AI hands you one, you place it on any empty square, then you hand the AI one of the remaining pieces. Placing goes back and forth.

You win the round the moment your placement completes a line of four — a row, column, or diagonal — where all four pieces share at least one trait: all tall, all hollow, all dark, and so on. It need not be the trait you had in mind, so watch every line.

The catch is the piece you give away: never hand the AI a piece that lets it complete a line. A win adds 1 to your streak and deals a fresh board; a full board with no line is a draw and keeps your streak; a loss ends the game. The AI looks deeper as your streak grows.

Tips & strategy

The danger in Quarto is almost never the piece you place — it is the piece you give. Before you hand one over, scan every line that already holds three pieces sharing a trait, and make sure the piece you pass completes none of them. If every remaining piece would hand the AI a win, you were forked a move ago; the cure is to avoid that position, not to escape it.

Think in traits, not in pieces. A line of four wins if the pieces agree on any single trait, so a row that is already all-dark is a threat no matter how the shapes and sizes differ. Late in the game a single square can sit on a row, a column, and a diagonal at once, so one placement may create three separate threats — that is how forks are born and why the board tightens fast after the eighth piece.

Count the shared traits of every line as it fills. A line with three tall pieces needs one more tall piece; a line with three dark-and-round pieces can be finished by any dark piece OR any round piece, which is twice as dangerous. Track which traits are still live on each line and you will spot the AI's threats a move before they mature.

The winning idea is the double threat. Aim for a position where two different lines each need only one piece, and the traits they need are broad enough that every piece left in the pool completes one line or the other. Then whatever you must give, the AI is forced to hand you a winner back. Building this quietly — while never giving the AI its own fork — is the whole game.