If your opponent is checkmated, you can't continue playing because it would be his move and he does not have a legal one.
If any draw situation occurs that is not stalemate, you can still continue playing.
I still don't know what part of "it's a chess rule" you don't understand.
If your opponent is checkmated, you can't continue playing because it would be his move and he does not have a legal one.
If any draw situation occurs that is not stalemate, you can still continue playing.