Sergash: Kaminer was 3 years older than Botvinnik, being born in 1908. So at the time of this game, he was 15 or 16 years old, while Botvinnik was 12 or 13 years old. Kaminer was a "Soviet study composer". Thirteen years after the actual game, he gave Botvinnik a notebook containing all his 75 studies. Because Kaminer apparently had problems with the Soviet regime, Botvinnik waited until Stalin's death to reveal the existence of the notebook. Kaminer's studies were published in 1981, in Rafael Moiseevich Kofman 's Izbrannye etjudy (1981).
Apparently this game was part of a training match opposing two young prospects? Let's have a look at it!
<6.a3> Strange move, which loses White's opening advantage. It was apparently played here for the first time. Black would probably not play Bf8-b4 and trade his good bishop on c3! Better to develop the pieces. The most played move here is 6.Nc3.
<6...Qb6?! 7.Qc2 ±/ ⩲> White having just lost a tempo, the timing was perfect to challenge the black bishop: <6...h6!> as played in the game <Gilles Tisin (1923) - Nicolas Fortuit (2057), 2nd Evry Open (France) 2006, round 6, 0-1>. After 6...h6, White can trade on f6 or retreat the bishop to h4 or f4, all 3 choices leading to complete equality. For instance:
A- <6...h6 7.Bh4 g5! 8.Bg3 Ne4=> Gilles Tisin (1923) - Nicolas Fortuit (2057), 2nd Evry Open (France) 2006, round 6, 0-1;
B- <6...h6 7.Bf4 g5! 8.Be5> (8.Bg3 transposes into A- above) <Nxe5> (also 8...g4 9.Bxf6 Qxf6 10.Nfd2 h5=) <9.Nxe5▢ Nd7=> Stockfish 8 - 64 bits POPCNT;
C- <6...h6 7.Bxf6 Nxf6=> Stephanie Lerke (1148) - Helin Tunc (1316), NRW Under 18 Girls Championship (Germany) 2007, round 7, draw.
<7...dxc4?! 8.Bxc4 ±> Botvinnik wants his King's bishop on d6, which is not feasible immediately (7...Bd6?? 8.c5+-), so he decides to first ease the tension in the center. A faulty plan... Normally, Black waits until White's king bishop has made a move before trading the center pawns. Here, we could suggest <7...Qa5+ 8.Nbd2! h6! 9.Bxf6> (also 9.Bh4 g5! 10.Bg3 g4! 11.Ng1!? Ne4=/ ⩲ other knight moves, like to e5 or h4, are also playable) <Nxf6 ⩲> Stockfish 8 - 64 bits POPCNT.
<8...Bd6> Botvinnik finally completed the development of his king's bishop as planned before the previous move, or maybe even earlier. Still, did he consider <8...c5!? 9.0-0 cxd4 10.exd4 Bd6 ±> Stockfish 8 - 64 bits POPCNT.
<9.Nc3?!> More precise appears to be <9.Nbd2! 0-0 10.Be2 ±> with the idea of playing Nd2-c4. Stockfish 8 - 64 bits POPCNT.
<9...h6> Botvinnik misses a chance to counterattack the center, like on the previous move: <9...c5! ±/ ⩲> now if White trades pawns, Black recaptures with the queen to avoid the queen-bishop fork by the white knight; while if White castles, Black does the same. Stockfish 8 - 64 bits POPCNT.
<10.Bxf6?! Nxf6 ⩲/ ±> It is better to retain this bishop: <10.Bh4! 0-0 11.e4 ±> threatening e4-e5 or 11.0-0 ± Stockfish 8 - 64 bits POPCNT.
<11.Rc1?!> Again there is <11.e4! Be7 12.0-0 0-0 ⩲/ ±> Stockfish 8 - 64 bits POPCNT.
<11...Qc7?!> Botvinnik did not realize he had a chace to equalize here, by returning to a recurring theme: the counterattack in the centre! <11...c5!=> Stockfish 8 - 64 bits POPCNT.
<12.Ne4?!> Why not <12.0-0 0-0 13.Ba2! ⩲/ ±> Stockfish 8 - 64 bits POPCNT.
<12...Be7?! 13.Nxf6+ Bxf6 14.0-0 0-0 ⩲> Geeze! <12...Nxe4! 13.Qxe4 Bd7=> Stockfish 8 - 64 bits POPCNT.
That is it for the opening phase, which was certainly not played by two theoreticians, but two kids! Botvinnik got somewhat outplayed in this part, mostly because of the moves 6...Qb6?! and the premature pawn trade on c4, giving Kaminer an important advantage.