Basic Rules

The essential rules to start playing Quaternity.

1. The pieces move as in chess.

2. The turn to move proceeds clockwise.

3. Pawns may move only one square per turn, even on their first move.

4. There is no castling.

5. Players may move only one piece or pawn per turn, even if in control of multiple armies.

6. Pawns that reach the rank or file furthest from their starting position must be promoted, as part of the same move and on the same square, to a piece (queen, rook, knight, or bishop) of the same colour. The player’s choice is not restricted to previously captured pieces.

7. Draws must be proposed by the player whose turn it is and must be agreed by all active players.

8. Explicitly declared alliances between opposing players are against the spirit of the mindsport.

9. The two advanced central pawns in each army may choose to move left or right on their first move; thereafter, for the remainder of the game, each advanced central pawn is committed to the chosen direction.

10. If an advanced central pawn captures a piece or pawn on the main diagonal, it retains the ability to choose its subsequent direction until it commits.

11. Checkmate is completed at the moment a player cannot defend their king with their own pieces and the checkmate position is established.

12. At the moment of checkmate, the defeated king is removed from the board, and their remaining pieces and pawns pass to the player who delivered the checkmate.

13. The remaining active pawns in an assimilated army retain their original direction.

14. Checkmate is awarded to the player who completes the checkmate position, even if their pieces are not directly giving check to the defeated king.

15. A player who resigns, loses on time, or forfeits leaves their army frozen. To checkmate them, the position is evaluated as if the army were still active.

16. In a game with more than two active players, if a player has no legal move, they may declare a pass and the turn moves to the next active player. This does not apply to checkmate.

17. A frozen king can be checkmated by an opposing king.