E38 Nimzo-Indian: Classical, 4...c5 (1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Qc2 c5 5.dxc5 Bxc5)

This was a correspondence game played at the Internet Chess Club. If I recall correctly this was a game to which my opponent challenged me to. I had completely forgotten that I had left the open for correspondence games option on at the mobile app, so there was a time when I saw an e-mail from ICC saying that I was losing one of my games on time, it made my look at what the situation was on the app. Instead of resigning the game, I quickly made a move in this game. I also noticed that one of the correspondence games that I had been challenged into had been aborted by my opponent due to me not noticing that the game was ongoing.

The game below went on in a decent manner for me until I played 13...Qc8, after which my position became completely hopeless quite quickly and I had to resign after 16.Qc3. The position that started my downhill can be seen in the next diagram.

My 13th move was not the losing move, but the game continuation ended my resistance very quickly. The game continued with the moves 14.Rac1 Rd8 15.Na4 and then I played the move that was the game deciding blunder 15...Bc5. I should have protected the pawn on b6 by playing 15...Qc7 instead.

[Event "?"] [Site "?"] [Date "2016.04.27"] [Round "?"] [White "rayosx"] [Black "Vierjoki, Timo"] [Result "1-0"] [ECO "E38"] [WhiteElo "2044"] [BlackElo "1626"] [Annotator "Stockfish 8 64 POPCNT (30s), TV"] [PlyCount "31"] [EventDate "2016.??.??"] 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 c5 {Nimzo-Indian Defense: Classical Variation, Berlin Variation} 5. dxc5 Bxc5 {E38 Nimzo-Indian: Classical, 4...c5} (5... Bxc3+ {Nimzo-Indian Defense: Classical Variation, Berlin Variation, Steiner Variation}) (5... O-O 6. a3 Bxc5 7. Nf3 b6 8. Bf4 {Nimzo-Indian Defense: Classical Variation, Berlin Variation, Macieja System}) 6. a3 a5 (6... Qa5 7. Rb1 Qb6 8. e3 a5 9. Ne4 Qc6 10. Nxc5 Qxc5 11. b4 axb4 12. axb4 Qc6 13. Nf3 Qa4 14. Qc3 O-O 15. Bb2 Qc6 16. Bd3 h6 17. O-O d5 18. Ne5 Qc7 19. Ng4 Nbd7 20. c5 h5 21. Nxf6+ {Utyupin,V (2122) -Usatchev,S (1855) Omsk 2009 1-0 (36)}) 7. Nf3 $146 (7. Bf4 Nc6 (7... e5 8. Bg3 Nc6 9. e3 O-O 10. Bh4 Be7 11. Nf3 d6 12. h3 Be6 13. Bd3 h6 14. Rd1 Nh5 15. Bxe7 Qxe7 16. g4 Nf6 17. g5 hxg5 18. Nxg5 Rad8 19. Be2 e4 20. Ngxe4 Nxe4 21. Qxe4 f5 22. Qf4 {Szilagyi,L (2126)-Lengyel, A Budapest 2000 1/2-1/2 (60)}) 8. e3 h6 9. Rd1 e5 10. Bg3 d6 11. Bh4 Be6 12. Ne4 a4 13. Nxf6+ gxf6 14. Nf3 Ke7 15. Be2 Qg8 16. g3 h5 17. Nd2 Rh6 18. Ne4 Bh3 19. Rg1 Bg4 20. Rd5 Bxe2 21. Qxe2 Qh7 {Silva,M (1770)-Fontes,C (2310) Brazil 1995 0-1 (36)}) (7. e3 O-O 8. Nf3 h6 9. Be2 b6 10. O-O Bb7 11. Rd1 Qe7 12. Na4 Na6 13. Bd2 Rac8 14. Bc3 Rfd8 15. Bd4 Rb8 16. Nxc5 Nxc5 17. b4 axb4 18. axb4 Na6 19. Bxb6 Rdc8 20. Qd2 Bxf3 21. Rxa6 Bxe2 {Jugow,A-Schuetzhold,F Wiesbaden 1993 1/2-1/2}) 7... O-O 8. Bg5 Nc6 9. e3 {Secures d4} b6 10. Bd3 (10. Rd1 h6 11. Bh4 Be7 $14) 10... h6 $11 {Black threatens to win material: h6xg5} 11. Bh4 Bb7 12. O-O Be7 (12... g5 13. Bg3 $14) 13. Rfd1 Qc8 (13... g5 14. Bg3 $14) 14. Rac1 (14. Na4 Qd8 $16) 14... Rd8 (14... Ba6 15. h3 $16) 15. Na4 Bc5 (15... Qc7 $142 $5 16. Qb3 Rab8 17. Qxb6 Qc8 $16) 16. Qc3 $18 (16. Qc3 Ne8 17. Bxd8 Qxd8 18. Bc2 $18) 1-0