A reader from the Netherlands contacted me last week for buying my book. He noted he favoured the line 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 Bf5 5.g4 Bg6 6.g5 Nd5 7.Nxe4 e6, now followed by 8.c4!! In an earlier blog, I prefered 8.h4, but the suggested move seems quite interesting. Chances are quite high that black develops a piece with 8...Bb4+ (diagram)
White now plays the surprising 9.Ke2!! and it is black who is in danger of loosing a piece, eg after 9...Nb6 10.c5 Nd5 11.a3 Ba5 (diagram).
The immediate 12.b4 runs into disaster after 12...Bxe4, but white should get a small advantage after 12.Kf2!!
I realise Tom Purser has written on this some time ago - also refering to the interesting article "The man who almost played 5.Ke2" in the archives of chesscafe.com, originally dated from March 2000 by Tim Krabbe on this theme. In this highly recommended article, Blackmar Diemer prodigies such as Diemer, Welling and Kasparov (...) show us the finer details of this line.
Unfortunately, black does not have to be so supportive and can deviate from 8...Bb4+ with 8...Nb6 (=+), or even 8...Ne7 (=) and 8...Nb4 (=). But it sure seems 8.c4 is an interesting alternative to 8.h4.