As white I play 1. e4 e5 2. Nf3 Nc6 3. Bc4, and against 3. ... Bc5, I do fine with the Evan's Gambit or Moller Attack, but there are a lot of people that choose a more counter-attacking scheme by playing 3. ... Nf6. I would never play 4. Ng5, which does win a pawn, but I will probably have to return the useless thing anyway, just so I can survive the later attack.

I read that 4. d4 was supposed to bring about a complicated and sharp battle, so I have been playing that move. I've played the move with some success, but I never looked that much at the theory. I was looking at it today, and was surprised when I saw this move:
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. O-O Bc5 6. e5 d5 7. exf6 dxc4 8. Re1+ Be6 9. Ng5 Qd5 10. Nc3 Qf5 11. Nce5 O-O-O 12. g4!?

What is the purpose of this move? Doesn't it just weaken your king and create a target on the g-file to attack? Due to the pawn on f6 the g-file will eventually be opened, if it is because White plays fxg7 or Black plays gxf6. It does get the queen to leave her post at f5 though is it really worth such a price? It also sets a minor trap (12. ... Qxg4+?? 13. Qxg4 Bxg4 14. Nxc5), but no one in their right mind would fall for such a trap. Yet I have seen the move in multiple games. What is it that I am missing about this move?

One less theoretical option is 4.d4 ed 5.e5. It's easier to play, gives white some reasonable initiative.

With the Max Lange, it's hard to talk about general principles. It's all about specific variations. So the question is, what does black do?

12...Qd5 13.Nxe6 fxe6 14.fg7 Rg8 15.Nf6 wins the exchange and white will try to keep the g-file closed with Bh6.

12. ... Qe5 is the main line. 13.Nxe6 fe 14.fg Rhg8 15.Bh6 (keeping the file closed) d3 16.c3 and now what?

The position is extremely double-edged, and may be a forced draw, but black has to walk a tightrope to get there.

For the record 12.Nxe6 is also a reasonable choice, although puts less pressure on the black.

The point is that black's pieces are poorly positioned for an immediate attack. White has 'the initiative' and isn't as worried about weakening his structure.