Briefly ON the Colorado Gambit Main Line (Seb Parker)
1. e4 Nc6 2. Nf3 f5 (Black aims to gain control of the centre by trading the f-pawn for white’s e-pawn )
Most variations are extremely sharp, if either player makes a misstep it can be fatal.
To play for any advantage, white is forced to accept the pawn. After black’s next moves:
3. exf5 d5 4. … Bxf5
the pawn is regained, and since white has moved the same pawn twice, black may quickly create initiative.
In order to stop black getting any breathing room to create a powerful attack, white is all but forced to play hyperaggressive, with
4. Bb5 Bxf5 5. Ne5
With the tactic of Nxc5 bxe6 Bxe6+ forking the rook and king looming, black defends c6 with Qd6, clearing the queenside to castle in some lines.
5. … Qd6
6. d4 (support e5) Nf6 (continue rapid development)
7. O-O (safety) Nd7 (contesting e5)
8. Bxc6 (creating weakness of doubled pawns) bxc6
9. Bf4 (looking for e5) Nxe5 (the purpose of Nf6-d7)
10. Bxe5 Qg6 (eyeing the king and c2)
And that is the mainline opening theory.
In this position:
Therefore white is ahead, positionally if not materially, but must launch his attack on the queenside, aiming for the c-pawns, and the black position can swiftly crumble. So the recommended next move is 11.c4, followed by Qa4.
There are some reasonable resources on youtube:
Some Indian guy with a lot of side lines assuming your opponent plays badly and showing how to capitalise:
A Master showing a more skilled analysis:
And from internet discussion forums, I found two fantastical grandmaster level games to see in this opening:
What a masterly finishing move!
Aside from the spectacle of a prepared queen sacrifice, in my opinion this game teaches a valuable lesson. The slight move order error of 4.d4 allows black the space to play e6, unlocking the king’s bishop. White is safer to play 4. Bb5 and 5. Ne5 and only later d4, as the pressure on c6 hugely delays black from playing e6.
There are many other minor points I researched, around certain thematic moves in sidelines, but this email is long enough so I’ll leave it there.