The objective is checkmate. Pieces move as in orthodox chess, with the exception of the additional piece, the "Zeppelin". The Zeppelin flies to any empty square orthogonally, ie. the rook-directions. It captures an enemy piece by landing immediately beyond its victim. On this board the Zeppelin's value corresponds to a bishop (preliminary estimate).

The Zeppelin piece is a weaker version of the Airplane, which was invented by R. W. Schmittberger for his Airplane Chess, 1981. The Airplane can also move in the diagonal directions.
There is an alternative variant with "Crabs" instead of pawns.

You can play Zeppelin Chess online and by e-mail here.