Review of the Ruy Cozio
The Cozio variation in the Ruy Lopez(4.Nge7) is a interesting sideline of the Ruy. Although it is not very popular, many strong players have played it with the Black pieces with good success. The strategems involved in the Cozio are different from any line in the Ruy Lopez, and inject fresh dynamics into the opening phase.
Personally, I used this line as a surprise weapon with decent results, and here are some thoughts.
1. Many players have not seen this line before, which gives black a good chance to equalize and gain an advantage if White does not know what he is doing.
2. Cozio is decent objectively, so even if the opponent knows how to respond, black will still get a reasonable position out of the opening.
Below are some of my own games with annotations for this line.
A few days later, White has some preparation against this line:
A well prepared player with the white pieces can get a pleasant position out of the opening, but black maintains a slight disadvantage, and the winner will be determined in the middlegame.