Daniele Gatti (Italy)
Not working 1. c8=Q+? Kxc8 2. a8=Q+ Kc7 3. Q2a5+ Kd7 and despite the two Queens in play, White’s position is losing.
1. … exd5 2. c8=Q+
(2. cxd8=Q+? Rxd8! And mate at next move [-+])
2…Kd6 3. Qb8+ Kd7 4. Qc8+ Kd6 5. Qb8+ Ke7 6. Qc7+ Ke6 7. Qe5+ Kd7 8. Qg7+ Re7 9. Qg4+ Re6 10. Qg7+ Re7 11. Qg4+ Kc7
Not working 11. … Se6 12. Qxf3 Sxd4 13. Qg4+ Se6 14. Kg2 Rf7 15. Kf1 Rf8 16. Qxg3 (= draw)
12. Qxg3+ Kb6 Black King obviously couldn’t capture the mad Queen, or it would have followed promotion in a8 with check, with consequent sacrifice and draw for stalemate. Thanks to this, White Queen was activated and now successfully captured one of the enemy pawns. But what do to now?
13. a8=S+! Thematic Move Ka7
White needs to capture both f2 and f3 pawns before Black forces could rearrange. This is impossible to do in one move because the pawns cannot be captured with check. Then, White underpromotes with checks and forces enemy King to reach the a8 corner, making him spend 2 moves to capture the Knight.
Thematic Logical Try 13. Qxf2? Kxa7! 14. Qxf3 Re1+ 15. Kg2 Se6 16. Qg3 Re2+ 17. Kf1 Ra2 18. Qd6 Sc7! 19. Qxc7 b4 20. Qe7 b3 21. Qb4 b2! and Black promotes. White Queen was misplaced after having captured the black Knight.
14. Qxf2 Kxa8 15. Qxf3 Re1+ 16. Kg2 Se6 17. Qg3! Now it works Re2+ 18. Kf1 Ra2 19. Qg8+! Ka7
After 18. … Ra2, occurs the same position as in the thematic try, but with black King in a8 and not in a7. This allows White to deliver check and gain a tempo, capturing the black Knight without losing control of the black B-pawn.
20. Qxe6 b4 21. Qe1! (= positional draw)
Nearly the same position as in the thematic try, but now white Queen can immediately guard the 1st rank, so the black pawn cannot be pushed furthermore.
Note: Every variation has been deeply tested with Stockfish 12 – 64 bit version, with 5-men tablebase installed.
AUTHOR NOTE: This is an improvement of my study published on 13° International Tournament UAPA (2020). An introduction was added and a slightly different configuration allows better development of thematic play.