A pretty challenging chess puzzle, because there isn’t a pre-determined number of moves. White to play and force a draw.
Solution
This is a long and tricky one to explain:
White plays 1. Bh4. This threatens 2. Bxf2, which results in white trading the bishop for black’s e and f pawns. Then black would be unable to prevent white from walking over and capturing the remaining pawn.
Black does have a line that appears to counter this – pushing 1. … d3. This threatens to promote the d pawn, while white’s king and bishop are still stuck dealing with the e and f pawns. If white continues to try to trade bishop for the e and f pawns by playing 2. Bxf2, black plays 2. … d2 and it would appear that white cannot stop both the d and e pawns from promoting.
However, white has a brilliant move that just allows black to promote:
- Bh4 d3
- Bxf2 d2
- Be1 d1
If black promotes to queen, it’s stalemate!
If black promotes to bishop, it’s clear that it’s a draw because black cannot force white’s king to move away from e1, preventing the e pawn from promoting.
If black promotes to knight, 4. Ke2 wins the knight or pawn, and then it’s clearly a draw.
If black promotes to rook, white can win the remaining pawn:
- Bh4 d3
- Bxf2 d2
- Be1 d1=R
- Ke2 Rb1
- Bc3 Rb3
- Bd4
This wins the remaining pawn, and rook+king vs. bishop+king is known to be a draw.