Just playing the same thing as I often tend to play for white lately.
3. e5 d5
In the case of en passant, I would take back with the c pawn. Then I'd have two center pawns vs one center pawn, which theory claims is good. Not that most people actually verify theory before employing it. But these thoughts aside, on to the rest of the game.
4. b4 e6 5. c3 a5 6. bxa5 Ra8xa5 7. Bf1d3 Ng8e7
I wanted to castle kingside, but it's not practical to move the knight to h3 due to Bxh3, gxh3 and broken castle. The f3 square is protected, so the only choice is to hop the knight twice before moving the bishop to castle.
8. Ng1e2
White also has only one side to castle to.
8... Ne7c6 9. O-O Bf8e7
Absolutely nowhere else for the bishop to go.
10. Bc1d2
This works towards the future of connecting the rooks, but I think in this game it ends up causing the issue for white of the knight on b1 obstructing the a1 rook for too long of a time.
10... O-O 11. c4 Nc6b4
If bishop takes, d2 bishop takes back. Doesn't seem like a problem.
12. Qd1b3 Nb8a6
Protects the double-attack on the b4 square.
13. a3 dxc4
The knight wanted to go to d5, forgetting that it's the only item in front of the rook. It does, and thus the Rook Gambit ensues.
