KEG: A great game by Schechter and indeed one of the very best games played by any of the contestants in the London 1899 tournament. The praise lavished on Schlechter for his closing combination by InspiredByMorphy is entirely justified.
In addition to his combinational genius, Schlechter here demonstrated his outstanding technique. Mason's 12...BxN was a mistake that gave Schlechter the advantage of the two bishops and control of the board, and Schlechter's fabulous play from that point to the end never gave Mason a chance to recover. The game is therefore a model for how to convert a positional advantage into a win. Bravo Schlechter!
For the third time in the tournament, Mason played the Petroff Defense (he had drawn with Tchigorin and beaten Janowski with this opening and was to defeat Bird in the last round with the Petroff as well). But only here against Schlechter did Mason face the "normal" line of 3. Nxe5. Mason did not handle this line very well at all.
Mason's 5...Nf6 was inferior to the normal 5...d5 (though Shirazi was to try this same line against de Firmian in the 1983 U.S. Championship) and Schlechter quickly got the better game.
Mason's 7...Bg4 was also bad, and Schlechter (in his only "mistake" in the game) should have simply played 9. h3 instead of his weaker 9. Nbd2.
Schlechter got around to playing h3 on his 12th turn, and it was here that Mason made his fatal mistake 12...BxN. As the Tournament Book notes, this exchange brought White's Queen into the game (and also gave Schlechter the advantage of the two bishops). The Tournament Book's proposed 12...Bd7 would have been better, and 12...Bc8 was probably best of all.
Schlechter immediately exploited his advantage with 14. Nf5. Mason's 14...Ng6 was inferior to 14...Ne6, and Schlechter immediately went to work with his powerful Bishops (aptly called "archbishops" by keypusher) with 15. Bg5. (Even better might have been 15. h4 immediately, but Schlechter's idea was also good).
With 16. NxB+, Schlechter obtained the powerful--and ultimately decisive here-- advantage of two Bishops against two Knights.
Schlechter's 19. Bc4+ did indeed force 19...d5 and block the Black Knight from going to d5--as noted in the Tournament Book, though I think that 19. Rae1 immediately was even stronger.
Mason was probably lost already, but his 20...Nf8 certainly hastened his demise (20...Nh4 was clearly better).
From this point on, Schlechter's logical winning technique is beautiful to behold. His 21. Rae1 built up his pressure via the e-file, and his 22. Bf5 chased Mason'e Queen to f7. Had Mason played 22...Nh4 here, Schlechter would have overwhelmed him with 23. Qh5, and not via the combination reflected in the Tournament Book beginning with 23. BxQ. Indeed, the proposed line as given would not have resulted in a win at all. Following the line proposed by Hoffer in the Tournament Book, if 22...Nh4 23. BxQ NxQ+ 24. gxN RxR 25. RxR NxB 26. Re7 Rd8 27. Bf4 Kf8 (27...Nf8 gives better chances) 28. Bd6 Ng6 Hoffer's 29. Ba3 would blow the win (in light of 29...Nc4). In this line, Schlechter would undoubtedly have played 29. Bc5 with an easily won endgame. In any case, Mason did not enter this line but played the "best" move of 22...Qf7.
With 25. h4, 26. h5 and the pretty 27. h6 Schlechter began his assault on the Black king.
Although my computer prefers 29. Qe3, I love Schlechter's 29. Kg2, making room for the Rook at h1 in many variations. Indeed, Schlechter could have won with 30. Rh1 had he chosen. Instead, he decided to go in for a winning endgame with 30. Qe8, another effective way to close out the game.