Steal the enemy flag and carry it home to win.
How to play
Each side has a flag hidden under its queen (white on d1, black on d8). Move any piece onto the enemy flag square to pick it up; the flag then travels with that piece. Carry it to your own back rank (rank 1) to win. If a carrier is captured, the flag returns to its home square. Check rules apply: you may not leave your king in check, and checkmate also wins. Stalemate is a draw.