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
Hostage Chess Hostage Chess Hostage Chess is a chess variant invented by John Leslie in 1997. pieces are not eliminated from the game but can reenter active play through drops, similar to shogi. Unlike shogi, the piece a player may drop is one of his own pieces previously captured by the opponent. In exchange, the player returns a previously captured enemy piece which the opponent may drop on a future turn. This is the characteristic feature of the game. Hostage Chess has tactical subtlety and "tends to favour the attacker". In 1999, David Pritchard called the game "the variant of the decade".