What are the strategic ideas of the Grob's Attack?
Is it meant to initiate a kingside attack?
Or is it meant to grab space on the kingside and use that space to maybe initiate an attack in the center or on the queenside?
The ideas behind 1.g4? are not sufficient to justify such a weakening first move.
The grand scheme
In an ideal world, White's strategic aim after 1.g4 is to build as much pressure as possible on the light squares in the center:
- They will fianchetto their light squared bishop, aiming at e4, d5 and even b7.
- Pressure can be reinforced with c4, Nc3, and sometimes Qb3, d3 or e4.
- Black's most natural defender of the light squares is a knight on f6. However, an early ...Nf6 will be ousted by g4-g5, kinda justifying White's first move.
But the main reason some White players are attracted to the line is that they gamble on their surprised opponent going for natural moves and stumbling into the Grob gambit's trap:
[FEN ""] 1.g4 d5 2.Bg2 Bxg4 3.c4 c6?! 4.Qb3
when all of a sudden the pressure on d5 and b7 gives White a huge initiative.
Note that all the moves played fit the grand scheme of attacking the light squares !
I dont know that there are any deep positional ideas behind it. Its mostly a tactical opening intended to be used as a surprise.
Positionally, I think the idea is just to develop quickly and put pressure on d5. Thats really about it.
It really comes down to what is the independent significance of g4 as opposed to g3 or d5 followed by g3. There isn't any. You could say it prevents f5 but black isn't really threatening anything with f5.