KEG: Steinitz' blunder on move 18 in grabbing Maroczy's f-pawn effectively ended the game by move 22. As knightfly correctly notes, Steinitz could safely have resigned after he was forced to give up his Queen with 22...Na6.
The stubborn Steinitz, playing the next-to-last game of his tournament career, played the same 5...Nge7 that he played in his 21st round loss to Schlechter (and that undeservedly brought him victory over Janowski in Steinitz's final game in Round 30).
Maroczy missed chances on moves 5, 6, 9, and 10 to dominate the board with d5. Steinitz could have thwarted this move had he played 5...exd5; with 6...Nxd4 (instead of 6...Na5, a move that was NOT "forced" despite the Tournament Book's claim); with 8...Be7 (instead of his actual 8...Nc6), or with 9...Nh4 (instead of his 9...Be7).
But Maroczy simply--and slowly--built a superior game. He could have done better, but Maroczy initially seemed satisfied with getting a good game rather than a quick crush.
Maroczy eventually lost patience. He finally played 11. d5, getting a strategically won game, but then overextended with 12. g4 (12. g3 was best). After 14. 0-0-0, Maroczy was only slightly better. The Tournament Book says that after 14. 0-0-0 Steinitz had nothing better than 14...Be7, but 14...f6 seems to thwart White's King-side prospects. The Tournament Book, however, is correct that Steinitz' 14...a5 was misguided.
Despite all his misfires, Steinitz still had a playable game after Maroczy's 18. RxB. Had he played 18...Qf6, he might well have weathered the storm.
I'm not sure what Steinitz was thinking in playing 18...Rxf2??, but there is no denying that this was the losing move. From that point on, Maroczy finished off the veteran Steinitz quickly and effectively.
After Maroczy's 22. Rf1, Steinitz's game was beyond repair. As keypusher has demonstrated, Steinitz could not have escaped with 22...Qd8. keypusher's line beginning with 23. Bf7+ is crushing. Another equally crushing line after 22...Qd8 is 23. Rf7, since 23...RxR 24. BxR+ would also have been murder (if 24...KxB 25. Rxg7+ leads to mate; 24...Kf8 loses to 25. Rxg7; and 24...Kh8 25. Rxg7 leads to mate).