Losing by Hallucination

     That's what happened to my opponent in an online game yesterday. As white I opened with the Grob Attack (1.g4) and, as often happens, my opponent (rated 1900+) got confused about the situation on the a8-h1 diagonal and lost the exchange. But, he put up manly resistance and because of his active N and B, combined with my weak Pawns, I found making progress difficult. So, I decided to return the exchange hoping it would allow me to make some inroads into his position with my R. It turned out to be a poor idea. But, after my opponent got the exchange back a funny thing happened...with 10 minutes left on his clock, he thought for six of them and then resigned. I don't know what he thought he saw, but it turned out that a post-game analysis with Stockfish showed the game was only a draw...five out of five in a Shootout. But what is really of interest is the position after 29...Rb8. I missed a nifty forced win.