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
Klubai
PRO Chess League
21 051 Nariai (-ių)
The RAR Newspaper Archives
29 Nariai (-ių)
Chess University
113 978 Nariai (-ių)
Xio Succ
2 Nariai (-ių)
4 Player Chess
54 756 Nariai (-ių)