PROBABLY WON'T FIX:
Embedded rules language not updated when language is set (in Analyse, Game and Problems)
If new live game starts in background, "new game" notify OK but not first move.

NEW VARIANTS:
http://history.chess.free.fr/rollerball.htm
  https://www.chessvariants.com/40.dir/rollerball/index.html

https://www.pychess.org/variant/shogun
https://www.chessvariants.com/incinf.dir/bario.html
  https://www.chessvariants.com/index/listcomments.php?order=DESC&itemid=Bario
  https://www.bario-chess-checkers-chessphotography-spaceart.de/
  https://le-cdn.website-editor.net/20ef5f800ea646c29f6852cfc5ceda07/dms3rep/multi/opt/BAR028-e15a849c-960w.jpg

Non-chess: ( won't add draughts: https://lidraughts.org/ )
gomoku, avalam, Fanorona https://fr.wikipedia.org/wiki/Fanorona
Yoté https://fr.wikipedia.org/wiki/Yot%C3%A9 http://www.zillionsofgames.com/cgi-bin/zilligames/submissions.cgi/92187?do=show;id=960

Later :
Qoridor (wider lines in another color ?)
Hexagonal variants (+ Gex game)