You play five white pawns against a black rook. Get any pawn to the far side of the board and you win. If the rook captures your pawns, or leaves you with no legal move, you lose.
A rook is fast and can pick off pawns in a line, so the game is about moving your pawns as a team and not leaving them hanging. It's a great first taste of planning against an opponent.
Three difficulty levels change how far ahead the rook looks.