About this opening
Nimzowitsch Defense: Colorado Countergambit Accepted is an opening in the Encyclopedia of Chess Openings,
classified under code B00. ECO group B (B00–B99)
covers semi-open games (1.e4 with Black playing anything other than 1…e5), with the Sicilian, French, Caro-Kann and Pirc/Modern at its heart. This particular variation is reached
after 5 half-moves from the
starting position, with the move sequence 1. e4 Nc6 2. Nf3 f5 3. exf5.
It belongs to the Nimzowitsch Defense family. Within that family this is a sub-variation (the Colorado Countergambit Accepted line).
The opening sequence in prose form: 1.e4 Nc6, 2.Nf3 f5, 3.exf5. From this position the encyclopaedia records no further canonical continuations — practical play branches into unnamed transpositions or returns to the parent line for alternative ideas.
Use the interactive board above to walk through the moves position-by-position. Click any move in the navigation to step backwards, or use the keyboard arrow keys. For statistical data — how often master-level players have reached this position, White's win-rate, draw frequency, Black's score — see the panel in the right column.
Caissly's coverage of B00 extends through every named sub-variation in this line and across all four locales (English, Spanish, Portuguese, Russian). Where editorial commentary exists for a specific variation it appears as the page body; otherwise the page presents the structural data, board, and statistics as shown here.