What other games or chess variants are useful to improve your chess skills? I know about Chess960, and you can play that online at lichess.org. Furthermore, I like playing Go as well. But are there any good variants and other ways to train that you use, and you know to work well?
I believe that studying Shogi added 50 points to my chess game.  They are related games and thus share some related concepts.  I believe Shogi showed me things about chess I had not understood before.