KEG: An alert Tchigorin capitalized on a series of errors/blunders by Cohn in this short game.Cohn got the better of the opening after Tchigorin's 13...b6. But then the game went downhill for Cohn. His 14. Qg3 blocked his g-pawn and was far inferior to 14. Qh3 or 14. g4. Tchigorin should here have played 14...Be8 instead of his 14...Bc8, but Cohn's 16. Ng4 was very bad (he should have played 16. Qh6). This lost a pawn, but Cohn had some compensation at this point.
Cohn erred again with 18. g3 (18. Ne2 was best), and after 19. Ne2 (instead of 19. Ne3), and Tchigorin's precise 19...Nf5, Cohn was probably lost.
Cohn made matters worse for himself with with 20. BxN (instead of 20. Qh3).
In this "difficult" situation (to quote Straclonoor), Cohn blundered twice, losing a piece with 27. Nf4? and then his Queen with his bizarre 28. QxN (if Cohn wanted to play on, he had to play 28. Qh3, thought this would have left him a piece down).
What went wrong for Cohn here? He must have seen the pawn fork with 27...g5. My guess is that Cohn overlooked that after 27...g5 Tchigorin's e8 Bishop defended the h5 Knight. I have no other explanation for Cohn's play.
I have said little about Tchigorin in this post. He did nothing brilliant or especially clever in this game; he just took advantage of every one of Cohn's mistakes.