crazy opening against the trompowsky

I've tried this before in Blitz, it's fun. :)

There are over 7000 games in the database with Bf4 but only about 100 continue g5 so it is not a novelty but it is still very rarely played.

An intentional near-fools-mate setup? Why not just avoid the Trompowsky alltogether with 1...g6? From there, you often can switch into King's Indian territory later. White can also opt to go for a Pirc, but 1.d4 players usually don't do that.

The near fools mate set-up turns out to be fine for black.  1...g6 is sound but it's a completely different opening.

have you tried the Bc1 g4 f3 gxf3 gxf3 e5!? line before?

im interested in how white players react against this piece-sac.

Yikes, haven't tried it yet, but want to. :)

I know, but the very reason the Tromp exists is that people wanted to avoid the KID. So what I meant was: Instead of trying to find a way to battle the Tromp, KID-players might think about preemptively forestalling the Tromp by playing 1... g6 and then maybe sneak in with the KID through the backdoor somewhat later ...

g6 is good if you know your opponent plays the trompowsky or if you are happy to play the pirc but if you want to play the nimzo indian then you have to play 1...Nf6.

I suspect the motivation for 2. Bg5 is not so much to avoid the KID but to avoid pretty much everything (KID, QID, Nimzo-Indian, etc.) and determine the opening on move two.  Of course, one should sometimes be careful what one wishes for... :)

I guess you're right. Nimzo-players also could avoid the Tromp by playing 1... e6, though. Now, of course, everything comes with a price. With 1...g6 you gotta be prepared for the Pirc, while with 1...e6 it's the French. However, my reasoning also included the thought that 1.d4-guys usually don't go into 1.e4-territory (and this goes especially for those who play Trompowski).

how about in the Bc1 line with 9.Kd3 consider playing after 12...e4 then 13.Nc3!? and giving back the piece but white seems to have too much play after 13...exf3 14.Nxd5 so maybe 13...Be6 is better.

Nimzo players normally answer 2.Bg5 with 2...e6 and prompt White to call his bluff...

Why cant black take the bishop on move 5.

I think the philosophy of the Trompowsky is sort of as follows: I want to play a sort of Colle System type opening with an ultra-solid pawn chain (c3,d4,e3), but I hate how bad my QB is then.  OK, I'll first exchange it off for Black's Knight, hopefully messing up his pawn structure in the process.  And if the Kt moves away to e4 (where else?), I'll just harrass it with something like f3 which will improve my position, gain time, and the Kt will STILL have nowhere good to go. Problem solved!

I don't think e4 is ever a given in the Colle, and anyhow, why wait? :)

I thought the point of the Colle was to eventually play for a quick e3-e4 after a few prep moves.  The Pseudo-Tromp video was pretty cool.  That was a good blitz strategy for Naka - Aronian spent a lot of time thinking...