Larry Christiansen has played and analysed his four games against Chessmaster.
At the 8th move, he shows a different possible continuation and says that
e6 (shown below) is forced for black. I don't see why black would be any worse if another move is played, so why is this forced? For instance, is
g6 not possible?
[FEN ""] 1. Nf3 c5 2. e3 Nc6 3. c4 Nf6 4. d4 d5 5. cxd5 Nxd5 6. e4 Nf6 7. d5 Nxe4 8. dxc6 Qxd1+ 9. Kxd1 Nxf2+ 10. Ke1 Nxh1 11. Bb5 b6 12. c7+ Bd7 13. Ba6 e6