Variants Puzzles and others: https://chessvariants.training/
https://altcodeunicode.com/alt-codes-math-symbols-italic-letters/
FoW: https://www.chess.com/blog/Illingworth/fog-of-war-chess-grandmaster-strategy
some crazyhouse study for future reference: https://lichess.org/study/OHSQPWgG
Klublar
4 Player Chess
51 011 agza
Fog of War
5 770 agza
Variants
4 523 agza
8 Player Chess
921 agza
4PC Teams
386 agza