Originally posted by Diophantus
The actual move preferred is Qb5. The reason? White has three safe moves after that (Qd2, Ng1, Qd1) and a whole host of ways to get mated. The software (not the engine, it doesn't matter what engine I use) seems to be choosing the move that gives white the greatest opportunity to cock up. I have now seen this happen three times in the past two weeks.
Clearly when you gave up the pawn on move 15 you probably had an inkling of this ending. My account on that site has been inactive for sometime, and given the lowly rating of your opponent I won't be going back there anytime soon. For the average strength club player who does not wish to use engines CC is dead.
1. d4 g6 2. e4 Bg7 3. Nc3 c5 4. dxc5 Bxc3+ 5. bxc3 Qa5 6. Qd4 Nf6 7. Qb4 Qc7 8. Bb5 Nc6 9. Bxc6 Qxc6 10. f3 O-O 11. Ne2 b6 12. cxb6 axb6 13. Be3 Ba6 14. Nd4 Qc7 15. Qxe7 Nd5 16. exd5 Rfe8 17. Qg5 Re5 18. Qh6 Rae8 19. Kf2 Rxe3 20. Rhe1 Rxe1 21. Rxe1 Rxe1 22. Kxe1 Qxc3+ 23. Qd2 Qc4 24. Ne2 Qc5 25. c3 d6 26. Qd4 Qb5 27. Qd2 1/2-1/2