Chakart :)

Checkered1 & 2 --> avec switch, coup roi sur roi.

Ambiguous chess
https://www.chessvariants.com/mvopponent.dir/ambiguous-chess.html
Need special highlight square --> similar to enlightened for Dark, in Board.vue
Also in notation, show only dest square for "opponents ambiguous moves".
Similar to Marseille-chess, white first move only 1 subTurn, do not choose a square.
Then black has a free first move, then choose a square, and the process goes on.

(Note: could simplify Marseille FEN, just indicate turn)

[Sittuyin (burmese chess) --> probably not]