Colorado Gambit: Opening Guide for White & Black


Table of Contents

Quick overview:

  • The Colorado Gambit is a subvariation of the Nimzowitsch Defense, arising after the move order 1.e4 Nc6 2.Nf3 f5. It is a rare opening that mostly has value as a surprise weapon.
  • If White plays accurately, they will have a superior position. However, any stumbling by White can give Black some interesting chances.
  • White usually accepts the gambit, and valuation greatly prefers White when the gambit is accepted.
  • The opening mostly has value in quick time controls, as Black has trouble finding compensation. Black may have a hard time playing the opening as there is a lot of opportunity to tranpose to other openings.

Introduction to the Colorado Gambit

The Colorado Gambit is a chess opening resulting after the moves 1.e4 Nc6 2.Nf3 f5.

Also known as the Lean Variation, this offbeat and aggressive line is a subvariation of the already rare Nimzowitsch Defense, in which Black plays the very uncommon 1…Nc6.

This Nimzowitsch already has a lot of potential as a surprise weapon, and the Colorado Gambit adds another layer to that. It is best used as a surprise weapon against opponents unaware of the lines.

The gambit has both safe and aggressive lines, but let’s be honest, if you’re playing f5 on move two, you’re probably best off keeping the game aggressive.

If you decide to play the Colorado Gambit, be aware that you won’t always be able to play it, as both the Colorado Gambit and its parent opening, the Nimzowitsch Defense, can transpose to many other openings.

Valuation is not great for Black after 2…f5. Engines give White a +1.5 advantage, so this is probably best avoided at classical time controls or in serious matches.

The Colorado Gambit Accepted-3.exf5

This is the best move by White. Black would actually prefer for White to decline the gambit.

After White takes, however, they have moved the same pawn twice, and now give up control of the center. Black should seek the initiative immediately. This is no time to go passive.


Black stakes a claim in the center and immediately threatens to regain the pawn as their light-square bishop is now activated.

Any attempt by White to keep the extra pawn would be awkward. The only way to do so would make for very awkward development, so White should give the pawn back.

4.Bb5 Bxf5

White should play very aggressively as well, to create some counterplay to Black seeking the initiative.


White threatens Nxc6 bxc6 Bxc6+, forking the king and the rook.

Black must defend against this threat so plays 5…Qd6, which can prepare for a queenside castle.

6.d4 Nf6 7.0-0 Nd7

White stakes a claim in the center with d4, Black continues rapid development with Nf6, White castles to safety, and Black contests e5 with Nd7.

8.Bxc6 White now creates a weakness on Black’s kingside by doubling pawns on the c-file. This makes the prospect of castling queenside less appetizing.

8…bxc6 9.Bf4 Nxe5 10.Bxe5 Qg6

Black’s latest move hits c2 and is staring down White’s king.

However, Black still does not have compensation for this dubious opening. Their king is still in the center, their dark-square bishop has not been developed yet and is stuck behind the e-pawn, and their c7 pawn is hanging.

Evaluation swings heavily in White’s favor here at +1.7.

An interesting sideline in the accepted variation

Let’s back up a bit and see what happens if White tries to defend the pawn with 4.Nh4 after 3…d5.

After 4.Nh4, White has thrown away their advantage, and Black is equal, if not ever-so-slightly better. Their knight is awkwardly placed on the side of the board. However, it seems that White has some tricks by bringing the queen to h5 to give a check.

Black continues with 4…Nh6, if 5.Qh5+ Nf7, and it is a dead-even game. White’s only developed pieces are far from the center on the h-file.

But if Black wants to keep the game aggressive (which they usually do if they’ve chosen this offbeat opening), they can play 4…e5.

5.Qh5+, and …g6 is actually the main move here.

6.fxg6 Nf6 7.g7+ Nxh5 8.gxh8=Q Qxh4

White has a significant advantage here, but they need to play carefully. In fact, there have been a few top-level games where Black has won.

Take a look at this example:

The Colorado Gambit Declined

Really, most games will have the accepted variation, so there is not a lot to say about if White declines the gambit.

White’s best move is to take, but if they decide to take, advancing the pawn is the best option with 3.e5. They still hold a slight advantage, though less than if White accepts the gambit.

From here Black’s best move is 2…d6.


The Colorado Gambit is a fun surprise weapon arising from the Nimzowitsch Defense. It is an opening that probably should not feature as your main opening as: 1. Black is not always guaranteed it will be played; and 2. It has a dubious reputation.

However, feel free to try it out in some online blitz games. You’re bound to catch a few people out with it.

Consider taking a look at some other gambits if you enjoy playing the Colorado Gambit:

The Smith-Morra Gambit

The Wing Gambit

The Benko Gambit

The Budapest Gambit

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