Blunder? Mate in one? HOW?


Sorry mate, the program is perfectly fine. Move 12 for black is a blunder because it allows Qf7 checkmate. Check others on your own

You are white, correct? The computer says after his move 12. ...d6 that is a blunder because you simply have a checkmate which you missed (Qf7#). Also, the program says that the best move for him is Bxf2 because if he plays Qe7 his bishop is lossed anyway so why not take a pawn and defend after (The capture is with check so you can't give mate!)

You are rated 850. The program that analyses these games is much higher rated. With the best will in the world, it is bound to make moves which you do not yet understand. In the case of 9...Bxf2+, Black sacrifices a Bishop for two pawns to launch a big attack against White's uncastled King. A typical line might run 9...Bxf2+ 10.Kxf2 Nxe4+ 11.Ke2 Qh4 and it is clear that Black has more than enough compensation for the material. He can develop his pieces quickly and White's King will never find safety. White's Kingside is undefended and Black's Queen and Knight will cause serious damage.
This is an excellent demonstration of why computer analysis is not likely to be very helpful for someone of your level. You need to analyse your own games, preferably with a stronger player who can explain the lines to you, rather than relying on complex variations spurted out by a machine which you do not understand. A computer is a tool which should be used only after self-analysis to pick up on silly blunders that were missed or to point out certain ideas.

So if I sum up :
- analysis with computer is useless for you, u'd better analyze with stronger player who will explain ideas.
- u criticize computer analysis when u don't have the level for that. A bit of humility wouldn't hurt u i think...

How many moves are you thinking ahead. Your program could very well be thinking 40 moves (20 per side) ahead, in every variation, no matter what move you play. Do you really think you're outthinking it ???

Black blunders by allowing white to mate. But I wouldn't expect the OP to see a mate as spectacular as that one.
Moral of the story: don't use the engine because you clearly don't understand it.