I was playing a casual game with a friend when I stumbled upon a move in the Bf5 variation of the main line Caro-Kann defense that seemed interesting (though interesting to me could be retarded to people rated above me). I was unable to find any games that explored it thoroughly. Hopefully someone has run into it before or has a master game or two that involves it, as I'm clearly not of the caliber to do that kind of analysis.

Here it is:

Just throwing it out there, maybe someone can tell me what's wrong with it. :)

I do understand that the usual main line is 5. Ng3 for white, but I have run into this quite a few times before and I would always respond 5... Qb6 without even considering the e5 pawn push.

There is nothing immediate wrong with this move. Certainly, at your level, my level, perhaps even 2000+ level this is not a bad move. However, when you reach NM and above, there is probably some space advantage or a poorer pawn structure or a tangled position or something for black... but our games are never decided by such factors.

Note that you're allowing 6. Nxb7. This seems to be the pawn structure advantage for white I was referring to. After 6. Nxb7 Qb6 7. Nc5 dxe4 material is even, which for us is perhaps all that matters.

I understand, though, there are things about the pawn structure that could be advantageous to black as well (assuming it's possible to use them properly), like the extra half open b-file and the advanced pawns giving black more space. It's kind of odd, though, I'll admit, because White and Black completely switch their usual roles.

Well, yes, you do have space and the b-file, but in particular I was thinking about the fact that black has three pawn islands in comparison to white's two, and that isolated rook pawn isn't going to do him any favours.

It is a perfectly good move, and I don't know which database you searched, there are 42 games in chess.com Game Explorer.

Here is the link before the move is played:

http://www.chess.com/explorer/index.html?id=996717&ply=9&black=0

and the link after the move is played:

http://www.chess.com/explorer/index.html?id=996717&ply=10&black=0

Well then, maybe I was using the search feature wrong. :/

Edit: Ah, I couldn't see any variations past that point because I need a premium membership. Probably something I should look into.

..e5 is the most aggressive move and is definitely what I would play. There's nothing wrong with it.

Actually 5...Qb6 is a more solid move. With 5...e5 Black is hoping to gain the attack by quickly getting pieces into play. However, if the attack fails Black will end up with really loose pawn structure, holes, and isolated pawns that can be attacked while White retains nice solid pawn structure.

Check out this game:

http://www.chess.com/games/view.html?id=2795401

I think that the aim of white's move Nc5 is to avoid theory or to try to get black to weaken the queenside pawn structure (so that a bishop on g2 becomes more influential) but I still think that black should play b6 here. White wastes many moves by moving his knight, which gives black time to use the a-pawn to damage white's queenside pawn structure.

Other than that, enjoy playing the Caro-Kann!