Black does not have to be cooperative when defending against the Blackmar Diemer gambit - a timely e5 can destroy white's ambitions 1.d4 d5 2.e4 dxe4 3.Nc3 e5! White has three options now : 4.Nxe4, 4.Nge2 and 4.Qh5 (diagram). We will analyse the Schneiders Attack today.
Can black take a second pawn an survive ?? If so, we should not consider the Schneider Attack anymore since it is well known that 4...Nc6 is also quite strong,
Let's look at 4...exd4 ( realising that black can take the pawn with the queen also, maybe even stronger than the text move ). I guess the only serious white option is 5.Bc4 (diagram), since both 5.Nxe4 and 5.Qe5 are countered by 5...Qe7.
Play continues 6.Bg5 Nf6 7.Bxf6 Qxf6 8.Nxe4 Qe7.
Black might have other options here, such as 8...Bb4+ 9.c3 Qf5 resulting in equal play.
And now the killer move 9.000 (diagram)
Black is a pawn ahead, so he doesnt have to take the piece that is offered to him, eg 9...g6 10.Qe2 Bh6+ 11.Kb1 Nc6 with equality.
But what happens if black does take the baite ? 9...Qxe4 10.Qxf7+ Kd8 11.Nf3.
Scheerer suggests 11...c5 only, indicating that 11...Bd6 was suggested by Kaissiber.
11...Bd6 12.Qxg7 and now a nice improvement 12....Rf8 (diagram)
Kaissiber suggested only 12...Re8, but the text move is better.
a/ 13.Ng5 Qf4+ 14.Kb1 Qf6 15.Nf7+ Rxf7 16.Qxf7 Qxf7 17.Bxf7 c5 (=)
b/ 13.Nxd4 Qe7 (=+)
c/ 13.Rxd4 Qe7 (=+)
d/ 13.Rhe1 Qf4+ 14.Kb1 Qf6 (=+)
e/ 13.Qxf8+ Bxf8 14.Rxd4+ Qxd4 15.Nxd4 (=+)
See we see that there is no advantage for the attacker in the Sneiders Attack.