Solution
Eric Angelini Europe Echecs 445, May. 1996
15+9. Which King was first under check?
Here is the solution posted by Richard.Sabey(at)swindon.gpsemi.COM to the retros-list.
Solution: The last check is of course b7xc8=B+.
White has made 7 captures. The promoted pawn came from g2, and captured on f3, e4, d5, c6, b7 and c8. There is only one other white capture, that of the h8R, the only missing black man which couldn't have got in the way of the promoting pawn. So that pawn captured Black's a8R, b8N, c8B, Q, g8N, b7P. (Black's b-pawn couldn't have promoted because Black had only one man, the f1B, to capture, but the b-pawn would have had to capture 5 times and get to g2.)
White's g-pawn might have played gxNf3 and fxNe4, but couldn't get past e4 without capturing something which couldn't have got captured before Black's b-pawn moved. (So White played Bc6, Black played bxBc6, and that freed the a8R, c8B, Q and other knight to get to e4 d5 b7 c8.) Therefore, before any white pawn moved, the only black men which could have got to f3 are the knights, so White must have played gxNf3.
When the black knight arrived at f3, no white pawn or bishop had moved, so the white king hadn't moved and no white man was missing.
So one check of the game was ... Nf3+. This was followed by White's first capture, and therefore Black couldn't have checked earlier, for then White would still be unable to move his king, and would have had to capture the checking piece (which would have to be a knight). White couldn't have checked earlier either, because no black pawn or bishop had yet moved, so black would have been unable to move his king and would have had to get out of check by capturing the checking man (which would have to be a knight), but I've already accounted for all captures, so no more are allowed. So ... Nf3+ was the first check of the game.
The White King was first under check !!
