OLTI27: This does sound like an interesting variant. There is another variant called Cursed Chess, which is somewhat similar, although not exactly the same. When a piece is captured it curses the square it is on so that enemy pieces are unable to cross it once the capturing piece leaves. Friendly pieces can still use the square though. The full description is here: http://www.chessvariants.org/difftaking.dir/cursed.html