Lesson
White to move. Main line: 1. d4 Nf6 2. c4 b6 3. Nc3 Bb7 4. f3 d5 5. cxd5 Nxd5 6. e4 Nxc3 7. bxc3 e6 8. Bb5+ Nd7 9. Ne2 Be7 10. O-O a6 11. Bd3 c5 12. Bb2 Qc7 13. f4 Nf6 14. Ng3 h5 15. Qe2 h4 16. Nh1 Nh5 17. Qg4 O-O-O 18. Rae1 Kb8 19. f5 e5 20. d5 c4 21. Bc2 Bc5+ 22. Nf2 g6 23. fxg6 Rdg8 24. Bc1 Bc8 25. Qf3 Rxg6 26. Kh1 Ng3+ 27. hxg3 hxg3+ 28. Nh3 Bxh3 29. gxh3 Rxh3+ 30. Kg2 Rh2#
Elite players normally resign once the result is forced, so the final mating move rarely appears on the score sheet. In this game Bogoljubow allowed Alekhine to complete the attack.
Alekhine first opens the h-file with 26...Ng3+! and 27...hxg3+. The bishop removes the knight on h3, after which the rook reaches h3 with check and follows the king to h2.
The final move 30...Rh2# is not merely a mate threat or an announced continuation: the checkmate was played on the board, making this game unique in World Championship match history.
Why checkmate almost never happens at this level
Elite players normally resign once the result is clear, so the final mating move rarely reaches the score sheet. Bogoljubow–Alekhine, game 8 of the 1929 World Championship, is generally recorded as the only World Championship game in which checkmate was played on the board.
How a mate ends up on the board anyway
A mate survives to the scoresheet when it arrives faster than the loser expects — the alternative to being mated has to be equally hopeless, or the mate has to be missed until it is unavoidable.
Replaying it, the final position is not an exotic pattern. It is an ordinary mating net, which is precisely what makes it a good record to have.
Play out mating nets in your own games even when a master would resign. The final moves make the pattern easier to recognize later.
Treat “the only ever” records carefully and check the cited source.
Source: World Chess Championship 1929 — https://en.wikipedia.org/wiki/World_Chess_Championship_1929
Source: Alexander Alekhine — https://en.wikipedia.org/wiki/Alexander_Alekhine
Source: Efim Bogoljubow — https://en.wikipedia.org/wiki/Efim_Bogoljubow