+https://www.chessvariants.com/d.betza/chessvar/trapdoor.html
+https://www.chessvariants.com/crossover.dir/koopachess.html
+--> Can a stunned piece capture? Maybe not. ...recover? After 5 moves? Never?
+
+Bicolour Chess (Gabriel Authier, 1958). v1 et v2 : (Roméo Bédoni, 1958)
+Kings are subject to check and checkmate by
+own as well as opponent’s pieces. The Q and
+QN are interchanged in the array
+.
+v2: y but a player may capture his
+own men (TODO: only v2?)
+
+Berolina Grid Chess, also known as
+Gridolina (originator not noted). A
+combination of Berolina and Grid Chess.
+Better than Grid Chess since Berolina pawns
+cross grid lines more easily. Described in
+World Game Review 10 as the most popular of
+the NOST combination games. (Nost-algia
+150, also Nost-algia 112 ‘not seen’)
+--> pourquoi pas, mais faudra pouvoir tracer des lignes sur plateau (Ball, Koth, Sittuyin, celle-là, Rococo)