Play the London System: g6 with Confidence

By playing g6, Black signals a King's Indian or Grünfeld-style setup: they'll put the bishop on g7 and often castle quickly. The key question is whether they capture on c4 or keep the centre closed. Statistically, the overwhelming favourite is 4…Bg7 (22,224 games), where Black simply develops. Your most common response in the engine's top line is 5.Nc3, then after 5…O-O you play 6.Rc1. That rook move is a hint: you are preparing to pressure the c-file, especially if Black ever takes on c4. If Black instead plays 4…c6 (3,928 games), they're holding a solid Slav-style centre — White scores 48.9% there. The good news: across all replies, your winning chances hover around the 50% mark, with draws rare (just 4.3% overall). This is a fighting opening where understanding the next few moves matters more than memorising long theory.

Stockfish's best move for Black is 4…Bg7, and the recommended continuation goes 5.Nc3 O-O 6.Rc1. Let's look at what that means for you as White. After 5.Nc3, Black castles (5…O-O), and your 6.Rc1 is a purposeful waiting move — you keep options open. You haven't committed your e-pawn, so you could still play e3 or develop the dark-squared bishop further. The idea is to be flexible: if Black plays …dxc4, you recapture with the rook on c1 (or with the bishop after e3). If Black doesn't take on c4, you can push e3 and build a classical pawn centre. With White scoring 48.6% after 4…Bg7, this is the main battleground. Expect a positional struggle where piece play and central tension matter more than tactics.

The database reveals two common Black mistakes in this position, and knowing them gives you a real edge. 4…e6 (1,389 games) is marked as an inaccuracy that loses roughly 0.8 pawns. The engine says Black should have played Bg7 instead. When you see 4…e6, Black is aiming for a French Defence setup but has wasted a tempo with …g6. You can take advantage by playing solidly — likely 5.Nc3, when …dxc4 is less attractive for Black because your development is ahead. 4…Nc6 (367 games) is also an inaccuracy with a similar penalty. That move blocks Black's c-pawn and doesn't help their development. White actually scores 54.5% after 4…Nc6 — your best winning percentage of any reply. After Nc6, simple development with 5.Nc3 or 5.e3 gives you a comfortable edge. Watch for these two moves and you'll already be ahead of many opponents.

Black's third most popular reply is 4…dxc4 (3,168 games), and here White scores a solid 53.5% — noticeably above your average. This is the Grünfeld-style capture: Black gives up the centre temporarily, hoping to attack your pawn on c4 later with …b5 or …Qxd4. Your usual plan is to recapture with the bishop after 5.e3, or simply play 5.Nc3 and let Black spend time defending the c4 pawn. In either case, you get a lead in development and a strong centre. With 53.5% wins, this is actually the variation where you have your best statistical chances among the major lines. If Black takes on c4, trust your development and central control — you are slightly more likely to convert than usual.