Ernst vs Regan, 1983
Written with Geoff Goodson.

Thomas Ernst bio: Thomas Ernst is a Swedish chess player, born in 1960. He became an International Master in 1984, and a Grandmaster in 1990 with a best rating of 2570 in 1992. He won the Swedish Chess Championships in 1993 and seems to favor the Sicilian Defense. In January 2004, 12-year-old Magnus Carlsen showed his extraordinary potential when he beat Ernst in brilliant fashion. Ernst has a Ph.D. in mathematics (Uppsala, 2002), with research interests in q-calculus, complex analysis, algebra and physics.
Kenneth Regan bio: Ken Regan an American chess player, mathematician, computer scientist and tenured professor in the Department Computer Science and Engineering, University at Buffalo. He earned his Ph.D. in 1986 at University of Oxford under Dominic Welsh. Beside computational complexity theory, his research interests include other fields of information theory and pure mathematics. Kenneth W. Regan holds the title of a Chess International Master [1].
References:
[1] https://www.chessprogramming.org/Kenneth_W._Regan
The game below starts its opening off like a Sicilian, but then morphs into a Modern Defense or an English Opening.
Tournament location: Eksjo, Sweden
White: Ernst
Black: Regan
- e4 c5 2. Nf3 g6 3. d4 Bg7 4. c4 d6 5. d5 e5 6. Nc3 Ne7 7. h4
Believe it or not, as of this writing, chess.com has 12 master games in its database with this sequence of moves. The move with the best outcomes for Black is 7. … h6. However, Regan played something else.
- … Bg4 8. Be2 Bxf3 9. Bxf3 h5 10. a3 Nd7 11. b4 Bh6 12. Bb2 Nc8 13. g3 a6 14. Be2 Ncb6 15. Na4 Nxa4 16. Qxa4 O-O
The game is now approximately even.
- O-O a5 18. Qb5 axb4 19. axb4 Rxa1 20. Rxa1 cxb4 21. Qxb4 Qc7 22. Bc3 Nc5 23. Qb1 f5
This weakens the protection around the King. Better is … b6 to improve Black’s defensive position.
- exf5 gxf5 25. Bxh5
This allows the next move. Better would have been Ra7, preventing Ne4. Black’s h-pawn is weak and can be grabbed later.
25 … Ne4 26. Qb4
Another possibility was 26 Be1 Qxc4 27 Qxb7.
26... f4 27. Be1
Black has a nice attack. The computer suggests an interesting option for White: give back the extra pawn to Black with 27 c5. Then, after Black plays Nxc5, White loses a pawn but gains time to solidify the defense of his king.
27 … fxg3 28. fxg3 Be3+
Black also could play … Qd7 here, threatening to infiltrate White’s King position.
- Kg2 Qh7 30. Be2
Here, 30 Qb1 may have been worthy of consideration. It essentially forces the exchange of pieces, defusing Black’s attack.
30 … Nf2 31. Bxf2 Rxf2+ 32. Kh3 Rxe2
Better was 32... Qe4
- Ra8+ Kg7 34. Qxb7+ Kh6 35. Qc8 Qg7
This is a blunder that loses quickly. Better was 55... Rf2, but White is better either way.
- Qe6+ Kh7 37. Qf5+ Kh6 38. Re8 Qxg3+ 39. Kxg3 Bf4+ 40. Kf3 Re3+ 1-0