This game (by the way, great invention of Mr. R. Wayne Schmittberger) follows the same rules as the standard Chess (starting position and piece movement) with these differences:
There is no check or checkmate.
The player who captures all opponent's pieces of one kind, i.e. all eight pawns, both knights etc., wins the game.
It is also possible to capture the opponent's king (and that finishes the game immediately since the king is the only piece of its kind). Because there is no check, a king can move to a square which is attacked by an opponent's piece or make a castling through such square.
Pawns can be promoted to any piece including a king. However, if the player promotes his/her last pawn, loses the game because he/she loses all pieces of one kind - pawns.