What is the hardest Chess Puzzle?
I noticed the puzzle difficulty on Chess.com goes all the way up to 4000, and the puzzles are indeed quite challenging, but why stop there? Theoretically, there is no limit on chess puzzle difficulty against an opponent playing perfectly, especially when the 50-move rule is ignored. However, no chess engine in existence can simulate a perfect player on the other side past a certain number of moves. The challenge is to design the hardest possible puzzle that involves a game against an opponent playing perfectly.
There exist many infamous positions within chess, I have a lot of favorites myself but wanted to find one far beyond both human and machine comprehension for this task. All board configurations with 7 pieces or less are already solved via Tablebase, hence the minimum requirement is an 8 piece board. There is no doubt that adding extra pieces to the board can extend the number of moves and complexity of any puzzle, so let's limit our scope to the first 8:
Proof of Concept: 9000+ Elo Chess Puzzle!
*Such a rating has no statistical significance, but playing 500 moves perfectly is not enough to win
Puzzle based on research by Marc Bourzutschky and Yakov Konoval.
White Wins solution exists in Tablebase after capturing the Queen on move 584.
This initial state begins the longest forced mating sequence known to chess, so far.
This is far beyond stockfish 16's capability to discover/analyze, so don't run Analysis->Review!
(Seriously, you will never get an output and only end up slowing down the site for all of us)
Imperfect opponent can still be beat from this position without thinking 500+ moves ahead!
Example: White Wins per Tablebase after just 17 moves! (Engine is not 100% deterministic)
As you can see, people still have the edge within chess in certain cases. I wonder if AlphaZero can beat Chess.com Engine in less moves but I'm willing to bet a sub-17 move solution against Engine will be discovered by a human through conscious reasoning/luck. Want to give it a shot?
