well, besides multi-movers, leaping pieces such as grasshoppers have
symmetric move patterns but assymetric retreat. and xiangqi cannon has
assymetric retreat when capturing but not when moving, which is one of the
things that makes it such a neat piece (and difficult to get used to).<P>
and incidentally any piece that move differently forwards than backwards
(these pieces don't have symmetric move patterns, at least not about the
x-axis) is going to have assymetric retreat. this includes lots of betza
pieces such as fBbR, fRbB, etc etc (i could go on and on) and shogi pieces
(which can of course be easily described in betza notation) such as the
gold, silver, copper generals, the white horse and the whale, etc etc.
