once the king moves, he can no longer castle to either side.
Crap. Forgot about that one. Oh, well, I'll remember it now.

Now we're even and I'm back playing defense.

I'm sure you'd like do a queenside castle, but you're gonna hafta move that bishop. So I'll protect where you might wanta move to and set up a short pawn chain...

P - K Kn 4