Blindfold Games are Harder than Games with Perfect Information

Resumé

Recently several researchers have shown an interest in the complexity of determining the existence of winning strategies in various games. The purpose of this note is to show that this problem is (probably) much more difficult for games in which the players lack perfect information about the state of the game. Familiar examples of games of this type include Kriegspiel (blindfold chess) and Battleship. In particular, we show that a simple one token game on graphs requires polynomial space to analyze in its blindfold version, although polynomial time is known to be sufficient for the version with perfect information.