If you had a Java-capable browser, you could play Triscacia here.
Keys "s"=save "l"=load "b"=back once

V R Parton, 1974. You may check one of your opponents, but you are forbidden to check the other. The first player to checkmate an opponent wins.

Hans Bodlaender's Chess Variants
Hans Bodlaender's Chess Applet

Ed's Chess Variants

Meet Ed

These are simple illustrations rather than strong opponents.

Bug reports? -- Thank you! Keep them coming!