how to castle on this app?


yeah, you move the king towards the rook. However, you can't if you have already moved either piece or are in check.

https://support.chess.com/en/articles/8557430-how-do-i-castle-on-chess-com
yeah, you move the king towards the rook. However, you can't if you have already moved either piece or are in check.
https://support.chess.com/en/articles/8557430-how-do-i-castle-on-chess-com