1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5 7.0-0 Nc6 8.d5 Ne7 9.Ne1 opens the King's Indian Defense: Orthodox Variation, Classical System, ECO E98. Across rating levels it shows up in 368,726 recorded games — enough data to map exactly where it succeeds and where it stalls.
History and Notable Players
It arises from the King's Indian Defense: Orthodox Variation, Aronin-Taimanov Defense. Among the most prolific White practitioners are Zdenko Kozul (51 games), Ruslan Pogorelov (50 games), Viktor Korchnoi (42 games). Black-side regulars include Wolfgang Uhlmann (25 games), Friso Nijboer (24 games), Mark L Hebden (22 games).
Performance Across Rating Levels
Popularity and results vary sharply by rating level. The 1200 bracket has 185 games (0.00% of all games at that level); White wins 55.1%, Black 37.8%, 7% are drawn. Move up to 1800 Elo and the share shifts to 0.01%, with White winning 53.8% versus Black's 42.1%. Among 2500-rated players the line appears in 0.10% of games and draws spike to 7%, indicating tight preparation.
Move Diversity and Theory Depth
Move choice is far from uniform in the King's Indian Defense: Orthodox Variation, Classical System. At 1200 Elo (185 games), the top reply is Nd7, played 44.3% of the time. Two other moves each take at least 5% of games, and the top three moves account for 80.3% of games. Entropy: 2.45. By 2500 (13,195 games), Nd7 dominates at 72.3% of replies; only one other move still reaches 5% and the top three moves account for 96.4% of games. Entropy drops to 1.19. That entropy collapse is the signature of a line where preparation pays off: at the top, players know the best move and play it.
Historical Trends
Year-over-year data tells you whether this opening is a contemporary fixture or a fading one. Adoption peaked in 2018 at 0.013% (24,250 games). By 2025 it sits at 0.005%, 62% below the peak and roughly back to its 2013 level, leaving the line flat over the full period.
Main Lines and Variations
After 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5 7.0-0 Nc6 8.d5 Ne7 9.Ne1, the established follow-ups are:
Each branch leads to a different middlegame character — the resulting pawn structure decides what kind of game you get.
Common Mistakes
- Drifting away from main theory — At 1200 Elo, the three most-played moves cover 80.3% of games, against 91.4% at 2000. The most popular deviation is c6 (played 12.6% of the time at 1200, much less so up top). It looks fine but quietly hands the better-prepared side an edge.
- Neglecting development — It can feel productive to make extra pawn moves early, but falling behind in piece development is what loses most amateur games — especially in open positions where active pieces find squares fast.
- Letting White own the centre — Hypermodern openings concede central space on purpose, but only if you strike back in time. Delay the counter-blow and you end up squeezed.
Practice on Chessiverse
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