Checkmate in Two Puzzles Test (Very Hard) - Chess.com
Chess.com - This is the hardest puzzle on Chess.com. Rated 3953. White to move. If you can solve it, AMAZING. 👏 If not, watch NM Sam Copeland explain the complex solution here
Hardest Chess Puzzle : [Checkmate in 1 move] Do you know all chess rules ? ( Board: Lichess ) - YouTube
The second hardest ever mate in 3 puzzle - Chess Forums - Chess.com
The Chess Problem That Was so Hard It Mad Garry Kasparov Himself Cringe