The UN, Retrograde Analysis, Geometrical Motifs, Purim, and Tal

Hilel Rivlin, Nahlat-Yehuda, Israel. What was Black's last move?
Source: Al Hamishmar, March 15, 1957.

As is well known, Israel is not exactly popular in the UN -- or, very often, with the USA, either. Israeli chess columns sometimes got back at the UN with their problems or comments. Here is an amusing example. The problem above was a published in Al Hamishmar during Purim (a Jewish holiday that is a combination between Halloween and April's fools' day) -- when not-so-serious problems or games are traditionally given.

The editors noted:

"The pieces in the four corners of the board in problem no. 1074 create the letters [in Hebrew, of course -- A.P.] of our crucial year, 5717 [in the Jewish calendar, starting fall 1956 -- A.P.]. We presume the special position is the result of a weird game, which was played according to the rules of the game, but against its spirit. We imagine the imaginary players of this Purim game were similar to the UN's secretary general."

In the solution (published two weeks later, on 5.4.1957) the editors added that "the solution is surprising" and "each of the pieces which make up the letters in the diagram plays a role and must stand where it is. We congratulate Rivlin for his creation."

By coincidence, the very same column has a report about a "young student", one Mikhail Tal, who has just won the USSR's championship with 14 points, ahead of Bronstein, Keres, Tolush, and others. This is one of the first -- perhaps the first -- mentions of Tal in the Israeli press.

(As usual, highlight the hidden text below for the solution).

The last few moves were: 1. Bg8-f5+ Ng6-f8.