Quartet

Goal

The board has 16 squares and there are 16 pieces, all different. Each piece combines four attributes: tall or short, light or dark, round or square, solid or hollow. The first player to line up four pieces sharing at least one attribute (four light ones, four hollow ones...) wins, in a row, in a column or on a main diagonal.

How it works

• You never choose your own piece: your opponent gives it to you.
• On each turn, place the piece you received on an empty square, then choose from the reserve the piece your opponent will have to place.
• On the first turn, the player who starts simply chooses a piece for the other.
• Placed pieces belong to both players: whoever completes the line wins.
• If the board fills up with no line, the game is a draw.

About the AI

The engine represents each piece with four bits and instantly spots the “deadly” pieces using attribute masks. It explores moves (a placement followed by a gift) with negamax, alpha-beta pruning, a transposition table and iterative deepening. As soon as the board empties enough, the search goes all the way to the end: at Master level, the endgame is then solved exactly.