Ziegler Defence

I'm going to have to disagree with 6.Bd3 being a sideline at this point in time. From where I'm sitting, it looks more promising than any of the Bc4 mainlines.

7.Bg5 would be my choice. This gives White a clear path to castle Queenside with tempo if Black attempts to win a second pawn. There's a very interesting line that can occur after 7...Qb6 that's strengthened my interest in this line. For instance:

Some ideas in this line. Bg5 has been my pet for a while here, because if possible it allows transposition into the Bd3 Ziegler from the O'Kelly defense (playing that move first instead of Bd3 is also plausible, and might be even better).

...I think the main reason 6.Bd3 has been a sideline is that it is obligated to lose a second pawn in many variations, and is always complicated and difficult, while 6.Bc4 has some tricks and traps that snare weak players... but if Black avoids those it can be tough. I'd definitely go with Lev Gutman's 7.Bg5 line if I were to play Bc4, over the Alchemy or the Classical.

A couple 7.Bg5 games that happened recently, in the Bd3 Ziegler.

Plenty errors in both, but you get the general idea. It can be volatile and fun.