Where the Jerome Goes, Strangeness Follows

Take a close look at the following Jerome Gambit game, particularly Black's 14th move & White's 15th move, and White & Black's 16th moves.

Poleshchuk, Nikolay Nikolaevich (2477) - Konovalenko, Anatoly Nikolaevich (2110)

RUS/FC/pr3 (RUS), 2020

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ 

4...Ke7 5.Bxg8 Qxg8 6.O-O d6 7.d4 Nxd4 8.Nxd4 Bxd4 9.c3 Bb6 10.a4 a5 11.Bg5+ Ke8 12.c4 Qxc4 13.Nc3 Be6 14.Nb5 Qxb5

15.Qh5+ g6 16.Qxg6+ 

16...Bf7 17.Qf6 Black resigned

What was happening? This was not blitz or bullet chess, it was correspondence chess played at a time control of 10 moves in 40 days.

The answer can be found on the International Correspondence Chess Federation website, where the tournament in which the game was played is described as "Zvezda Forbidden chess".

Yury Bukayev, chess friend and contributor to this blog - a Sherlock Holmes of chess openings, including the Jerome Gambit -  helped me to understand the nature of this pseudo-chess tournament. He identified "forbidden chess" and sent a link to a discussion on a Russian language chess forum

What is "Forbidden Chess"? This is the same classical chess with all the rules, goals and objectives, but with one important addition: during the game, each side can ban the opponent's retaliation three times.

Note No. 1.A ban can be imposed along with the next move on the opponent's retaliatory move. Making his move on the ICCF server, White (Black) in the message indicate which retaliatory move they prohibit. For example: White makes the move 1.e2 - e4 and writes in the message - "ban 1....c7 - c5". This means that Black can answer whatever he wants, but not 1….c7 - c5. 

Note No. 2.The forbidden move can be indicated by each side only three times, but once in each allotted period. The first period: from the 1st to the 10th move inclusive, the second - from the 11th to the 20th move inclusive, the third - from the 21st to the 30th move inclusive. That is, when Black makes his 30th move, he can make a ban for White for the last time (if he did not use it earlier from 21 to 29 moves). Starting from the 31st move, the ban cannot be imposed. The ban rule is voluntary. If one of the parties (or both) did not use the ban in the first period, then it seems to automatically disappear. But two more prohibitions remain at the disposal: one in each of the subsequent periods. The same happens further.

Note No. 3.A ban cannot be made if the opposite side has only one move left. A ban can be made when the opponent has at least a minimal choice. 

Note No. 4.All the rules of classical chess (checkmate, stalemate, castling, threefold repetition of a position, endgame tables, and so on) in forbidden chess are valid. After White's 31st move, forbidden chess really turns into classic, since the forbidden rules can no longer be applied.

Now the game makes more sense: we can see that White and Black, in turn, were forbidden from capturing the enemy Queen. My guess is that White also prohibited 4...Kxf7, turning the game into a Jerome Gambit declined.