zydeco: A Nimzowitschean win for Spassky.
Ivkov says that he hoped to draw this game -- and offered a draw on move 11.
In the opening Ivkov has a strong-looking center but no flexibility. Spassky undermines his pawn center very effectively.
"Ivkov's bland play urged me forward, and I decided to create at least some difficulties for him before he arrived at a peaceful port," is Spassky's comment to move 16.
White's chance was at move 18. Ivkov could have played 18.dxc5 bxc5 19.b4 and then with 19....cxb4 20.Nxb4 Qc8 21.Qxd6 Be5 white is a pawn ahead in a complicated position. If 19....Bd4 (what Ivkov was afraid of) 20.Bxd4 cxd4 21.a5 and white is doing well.
Ivkov's move, 18.Nf2, allows black to simplify and take out all the oxygen from white's position. White is nearly in zugzwang for the last few moves of the game.