Graveyard chess
Graveyard chess is a variant of chess where, instead of being removed from play, captured pieces are sent down to a 'graveyard' to have a second chance.
Pieces that are captured are sent down a level to a 'graveyard' - essentially another board. It is placed in the same position i.e. a pawn captured on e4 moves onto e4 on the next board down. There can be many graveyards. If a piece that is on a graveyard makes a capture, it moves up a level - to the same position. If a piece is on the lowest graveyard and is captured, it is removed from play.
To indicate which board a piece is on, a number prefixes the move notation, with 0 as the top board, and in ascending order (i.e. the first graveyard, just below the top board, is numbered 1; the next one down 2 etc.) . A move up or down need not be indicated - it is indicated by the fact a capture has been made. It is possible for a chain of captures to be made - this is indicated with an asterisk followed by a number at the end to show the number of captures, provided there is more than one capture made.
Example (see right also): After 1. 0Nf3 0d5 2. 0Nc3 0e6 3. d3 0Bd6 4. 0e4 0dxe4, White's pawn has dropped to 1e4, instead of being removed from play. White captures back with his pawn from 0d3 - 5. 0dxe4. However, Black's pawn drops down to 1e4, capturing White's pawn in the process, and sending it out of play. Also, the black pawn ascends because it made a capture, capturing the pawn White just used to capture it - the tables are turned! Now White's pawn descends to 1e4, and Black's pawn remains on 0e4! The move is not 5. 0dxe4, but 5. 0dxe4*2??. White ends up removing his own piece from play, and sending another down a level. Often chain captures will have to be computed to see the consequences - which can be very bizarre. Sometimes initiating a chain capture can be very dire.
Apart from the ascension and descension of pieces as they capture and are captured, the fact that there are multiple boards, and slight alterations to notation, the game is exactly the same as chess.
Graveyard chess has one variable: the number of graveyards. More graveyards makes for a longer game, with more allowance for being captured. Fewer graveyards makes for a shorter game, with less allowance for being captured. One to three graveyards is an appropriate number for most games. It is worth noting that Graveyard chess with zero graveyards is identical to orthodox chess.