Capitalised on black's mistakes

At one point I thought I lost the game.

But my opponent made serious blunders letting me in back into the game.

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5 6. Nf3 a6 7. Be2 Be7 8. O-O O-O 9. Re1 Nbd7 10. Be3 b5 11. a3 Bb7 12. Bd3 Nc5 13. b4 Ncxe4 14. Nxe4 Nxe4 15. Bb6 Nxf2 16. Bxd8 Nxd1 17. Raxd1 Rfxd8 18. Be4 d5 19. Bf5 e4 20. Nd4 Rac8 21. Bxc8 Bxc8 22. Nc6 Bg4 23. Nxd8 Bxd1 24. Rxd1 Bxd8 25. Rxd5 Be7 26. Re5 a5 27. Rxe7 f5 28. bxa5 {black resigns} 1-0



12 --> ..Nc3 was a nice move by him.
20 --> ..Rac8 is where is blunder starts.