Natural enough, but the c6 knight can't effectively defend e5 or d4, and may end up chased by the d-pawn.
4. d4 d5 5. exd5 Qd8e7
? Qxd5 would've been better. Now the knight is forced to move and the black king's bishop is bottled up.
6. Bf1e2 Nc6b4 7. c4 Bc8f5
Natural, prepares for Nc2+ followed by Nxa1, and for O-O-O.
8. O-O f6
? understandable in defense against Ne5, but weakens the king position and blocks the black king's knight from coming to play. Better would've been Nf6.
9. Qd1a4
There are no good defenses against this check. Qe7 might've been best, forcing white to react to it and letting the black bishop come to the field.
9... c6
doesn't suffice.
10. dxc6 b6
A good move. bxc6 a3 and then Qxc6+ followed by Qxa8 would've been bad. Nxc6 d5 even worse. And of course, Qxe2 Re1, so the bishop is not actually undefended.
11. Be2d1
defends c2 square but more importantly allows opens the e-file for Re1 and eventually Rxe7.
