Line Of Sight Chess

LineOfSightChess is like standard chess except that you can only see the opponent's pieces if you can attack them with one of your own.

This was the challenge at the XpCodeSprint held in PortlandOregon in April 2005.

See our code at http://cvs.sourceforge.net/viewcvs.py/remorse/losc/
SetupForCodeSprint

Related versions of GameOfChess.

This is more commonly called DarkChess. See, for example, http://www.gamerz.net/pbmserv/darkchess.html where it has been established for some considerable time.
This is a variant of the ancient and venerable "Kriegspiel" (German for "wargame") chess variant, in which neither player can see the opponent's pieces at all; a referee tells them what happens when they attempt to move. Invented in 1899 by Michael Henry Temple (1862-1928). It's worth mentioning that the German military had been enthusiasts of military simulations under the general name of "Kriegspiel" for over 50 years by then, and that Temple was adapting that existing name and notion to the chess board. http://www.chessvariants.com/incinf.dir/kriegspiel.html
http://www.chessvariants.org/other.dir/fog_of_war_chess.html -- pc computer program that implements line-of-sight visibility rules
http://www.dodccrp.org/events/2000/5th_ICCRTS/cd/papers/Track1/014.pdf -- warfare research conducted by playing chess on two boards with a human unequally relaying information between boards.

A chess variation I used (long ago) when teaching beginners who couldn't seem to anticipate what the opponent would do next was "ReverseChess?" where you played the pieces from the other side of the board, in other words, if the white pieces were set up on your side of the board, you played the black pieces.

After a few games done this way the ability to spot strategic and tactical weaknesses in your own position improved, often by quite a lot.

I recently envisioned an "atomic-age" variation of chess. Play by the normal rules, but whenever there is a capture, both pieces die and the square the capture was made on becomes "radioactive wasteland" (indicated by laying a checker or poker chip on that spot) -- nothing can land on that square, though pieces that move multiple squares in a single turn can pass over that square.

KeithRay