this idea came to me just as a theorical example, while saying chess is a game that give a lot of penalty for each error, and not so much reward for great moves.
so i imagined this:
a crazyhouse game, where instead of having free to put the pieces that you capture, you will have free to put the pieces that you lose (so losing a piece is actually good for you most of the times).
but to win the game you can only give the checkmate with a knight (or maybe just a knight move including a discovery checkmate), while every other checkmate you give with other pieces would be considered a draw game. this would force the player to elaborate very complex strategies to get a win, you can't just count on "make less errors than your opponent". or anyway it seems an interesting idea to me.
it would need some limitations of repeated checks like with a queen captured by the king again and again just to force a draw, but preventing a check when putting a piece seems too much limitating, i will think a possible solution to that