5.Bb5+ looks like a strong move. If 5...Bd7 then 6.Bxd7? is a patzer's move, but 6.ed5 looks good: 6...ed5 (6...Bxb5? 7.Nxb5 ed5 8.Qxd5 is a routine pawn steal) 7.0-0 with a good variation of an IQP.

5.ed5 is also strong: 5...Qxd5 6.Nc3 Bb4 and now 7.Nb5! is quite awkward for Black.

If Black wants to play ...d5 that early, then his best try is 1.e4 c5 2.Nf3 Nc6 3.d4 cd4 4.Nxd4 d5!? which is certainly provocative, but not easy at all to refute.

6...Bxb5 7.Nxb5 Qa5+ then either knight on c3 is a safe pawn up (8.N1c3 looks "better"). If 6...Qa5+ then 7.Bd2 (7.Nc3 is also strong enough) and Black can pack and go home.

To my poor positional understanding, the whole idea here is really unplayable. The "best" position with the IQP is simply miserable.

But 2...Nc6 3.d4 ed4 4.Nxd4 d5!? is anti-positional, but mighty playable. It has a decent record, even against GM opposition.