Is C4 a good move here? Or does white risk overextending?
I gotta admit, I initially assumed this was !AnarchyChess and severely misinterpreted the question!
Wouldn’t that make whites b4 pawn loose? The black knight could pop in a take it but not sure how complicated that would be or if it’s worth it.
But to be fair if it goes
c4 qxb4
xd5
and white’s up a knight and just down a pawn plus queen is in danger so they have to move it
As far as my beginner eyes see that’s a decent +2 advantage for white
Alternatively if they take with knight, than white can threaten the queen and block the queens defens of the knight with c5
Oh but I do see a line where you are correct.
If it goes
c4 Nxb4 c5 Qe7 h4 Na6
though maybe the Knight ends up blocked in that position and potentially lost. I don’t have the vision too see that far.
c4 Nxb4 c5 Qe7 h4 Na6
After c5 Qe7
Nxe6 and it's hard to find a response. Not taking the knight sacrifices the exchange of a rook for a knight and taking the knight runs into an infiltrating rook while also losing the b4 knight. I don't think Nxb4 is a move honestly.
Most likely continuation seems to be something like
c4 Nf6
c5 Qe8
Which gives white a good looking position. And cramps black. But should white avoid this kind of play for fear of black getting in behind their pawn lines?
C4 nb4 -> black queen also threatens b4
C5 Qe5
Rxe5 ... black resigns because they lost a queen for nothing.
I really don't think black can take on b4 after the c4 push. c5 cuts the support and now the queen is threatened and has to move which will result in e6 (attacked 3 times) falling or black's queen being hunted.
Qe7 still runs into Nxe6 and black can't take back because e6 is attacked too many times. As suggested above Nf6 is the most sensible response after c4, black needs that knight to defend.