Kriegspiel (chess) illegal, the player tries again; if it is legal, that move stands. Each player is given information about checks and captures. They may also ask the referee if there are any legal captures with a pawn. Since the position of the opponent's pieces is unknown, Kriegspiel is not a game with perfect information. As each player cannot see his opponent's pieces, the game is sometimes referred to as "blind chess". There are several different rule sets for Kriegspiel. The most widespread rules are those used on the Internet Chess Club, where Kriegspiel is called "Wild 16". The rules are as
Chess 2: The Sequel system. Each player begins the game with three stones. Whenever a capture is made, the defending player may initiate a "duel." In a duel, the players secretly "bid" up to two stones. After revealing the bids, the stones are removed from the game; if the defender spent more stones than the attacker, both the attacking and defending pieces are captured. More stones may be earned by capturing enemy pawns. Sirlin's intention with this mechanic was to allow players to dynamically evaluate the worth of their pieces throughout the match. A video game version of "Chess 2" was released on Ouya