Sämisch Variation

The Sämisch Variation, sometimes spelled Saemisch, was introduced by Friedrich Sämisch in the 1920s. It is the only major King's Indian system in which White may castle long. The f3 pawn makes e4 secure and rules out ...Ng4, but the king's knight is pushed to e2, and the g1–a7 diagonal can become a liability for a king castled short. Botvinnik played it against Tal in the 1960 and 1961 title matches, and Karpov against Kasparov in 1990. It has since become less common than 5. Nf3. Black almost always replies 5...O-O, and engines rate the position as roughly balanced.

The main branches arise after 5...O-O 6. Be3. In the Orthodox Variation, 6...e5, White either closes the center with 7. d5 or keeps the tension with 7. Nge2; Kasparov favored this defense for Black. The Sämisch Gambit, 6...c5, was once thought dubious but now has a good reputation. After 7. dxc5 dxc5 8. Qxd8 Rxd8 9. Bxc5, Black's activity is considered sufficient compensation, though White can often steer the game toward drawn lines. In the Panno, 6...Nc6 7. Nge2 a6 8. Qd2 Rb8, Black waits to see White's plan: ...b5 answers queenside castling, while ...e5 meets a more cautious setup. 6. Nge2 is the Bobotsov-Korchnoi-Petrosian Variation.