Ironclad is a commissioned game from Frank Lantz for the game design textbook "Rules of Play", by Katie Salen and Eric Zimmerman. Ironclad is played on a 6-by-8 checkerboard, using checkers on the spaces and go stones on the intersections. The checkers represent battling armored robots, and the stones represent arguments in a philosophical disagreement between two logicians. These two sub-games, battling robots and arguing philosophers, are played simultaneously on the same board. You win by winning either sub-game. In the robot sub-game, you start with your robots on your side of the board. On each turn, you can either move a single robot or fire on an enemy robot with all the friendly robots that are within range. You win if one of your robots reaches the opponent's side of the board. In the philosophers sub-game, you attempt to make an unbroken string of stones in your color from one side of the board to the other. On each turn, you place a single stone of your color, if possible. Otherwise, you move a single stone of either color. If neither is possible, then your opponent wins. The sub-games interact in two ways. First, a stone cannot be played on the corner of a space containing a robot. Second, if a space containing a robot has one or more stones on its corners, that robot receives a defensive bonus when attacked. The most novel aspect of Ironclad lies in the choice of which sub-game to play in. On each turn, a player makes two moves, one in each sub-game. However, the player only gets to decide on the move in one of the sub-games. The player's opponent gets to decide on the player's move in the other sub-game. So the player chooses one of the sub-games and makes a move in that sub-game, then the opponent moves for the player in the other sub-game.