King's Indian Attack: Sicilian Variation: what to play after Bg2?

In the King's Indian Attack: Sicilian Variation (ECO A08), Black faces a choice against White's kingside fianchetto setup. The engine marginally favors g6 with an evaluation of +0.15, aiming to blunt the long diagonal by mirroring White's structure, though Nc6 remains the overwhelmingly popular practical choice. Black can also develop solidly with moves such as Nf6 or e6.

Practical Popularity Versus the Top Engine Choice

Human play diverges sharply from the engine's primary preference in this position. Out of 3,744,280 recorded games, Nc6 has been selected in 75.7% of encounters (2.83M recorded), yielding a White scoring rate of 55.1% alongside an engine evaluation of +0.25. In contrast, the engine's top move, g6, appears in only 0.9% of games (34K recorded), where White scores 53.6%. By playing g6, Black neutralizes the pressure of White's bishop on g2 by preparing their own fianchetto on g7.

Illustrative Lines from the Main Variations

Engine analysis indicates that play remains dynamically balanced across several key setups. Following the top choice g6, the engine illustrates g6 c4 d4 b4 cxb4 a3, where play quickly shifts to queen-side space and pawn tension. Against the heavily favored practical continuation Nc6, the engine tracks Nc6 d4 e6 O-O Nf6 c4, returning the game to central maneuvering typical of Sicilian structures.

Alternative Central Setups

Black frequently chooses traditional central development before committing the queenside knight. The move Nf6 is played in 15.1% of games (566K recorded, +0.21 eval, White scoring 54.4%) and is illustrated by Nf6 O-O e6 c4 d4 d3. Similarly, e6 accounts for 8.3% of games (312K recorded, +0.18 eval) with White scoring 56.8% in the continuation e6 O-O Nf6 c4 d4 d3. Lastly, h6 rates at +0.40 in the illustrative continuation h6 O-O Nf6 c4 d4 b4.