Marek Ctrnact improved the zrf.

Mephisto is played on a special board with pairs of numbered squares. Captures are not made by replacement. Rather, when a piece lands on an empty square, any piece on the corresponging numbered square will be captured. Warning: it is possible to capture your own pieces.
Pawns move one space diagonally, can not move two spaces on the first move, and still promote when reaching the far rank. There is no castling.
Other than this, normal Chess rules apply.