Doodle Defense is a tower defense game played on a white board and interacted with by drawing with dry-erase markers. Players draw mazes and towers on the whiteboard to stop projected foes. Colored circles represent towers which attack the foes, and black lines represent walls that the player can use to redirect the foes around their towers. By allowing players to draw their board instead of just placing towers with a mouse, the game encourages greater creativity and promotes new strategies for players. The experience is enhanced by the magical feeling of seeing projected game elements interacting with real word drawings.