Duel Reality is a digitally enabled sword-fighting game played with fake swords and top hats. The data coming from a body sensor (think heart rate sensors etc.) determines where the opponent should hit you. However, you do not see this information yourself, so you will have to observe your body to figure out what your body is doing. If players had perfect knowledge of this data, they could easily defend themselves. However, since a player has no direct feedback from the sensors, their defense is weakened by their imperfect knowledge.