On Fri Nov 13 2020, 15:10, James Propp <jamespropp@gmail.com> wrote :

Ordinary chess forbids moving into check (and hence from moving into checkmate), which means you automatically lose if there's no way to avoid moving into check. Is there a variant of chess in which you're not allowed to make a move that would cause you to lose 2 moves in the future?

In Blitz chess, according to FIDE rules until 2017, a player could make an illegal move and the opponent would win if he noticed this on his turn (otherwise the referee should call the game a draw). So in particular one could ignore a checkmate situation (the rules do not say that you have to announce check or checkmate, many high class players consider it is even very impolite to announce check) and instead make a move which leaves your king under attack. The opponent could then take the king and thus win the game. This was actually very popular, but a somewhat ancient way of proceeding which was officially deprecated. The opponent should, instead of taking the king, rather claim his win because the other player had made an illegal move. However, e.g., the German Chess Federation had ruled that taking the king was a way of signalling the opponent's illegal move. (see https://www.schachbund.de/news/hau-weg-den-koenig-wirklich.html). The player might get a blame for doing so, but would nonetheless win the game. So with these older rules one player could make a move that left his king in check and then his king could've been taken. However, the next move should be either the king being taken, or the game ended as a draw by the referee. (When there's no referee, I assume it often happened that both of the players didn't notice the check situation and continued playing otherwise. Probably the guy who was in check would remark it soon after and move out of it, and the game would thereafter continue "legally".) - Maximilian (Replacing 2 by larger integers, we get a game in which the legality of

a move can become rather murky!)

Jim