Old Indian Defense
The Old Indian is considered sound, though developing the bishop at e7 is less active than the fianchetto, and it has never attained the popularity of the King's Indian. Some King's Indian players will use the Old Indian to avoid certain anti-King's Indian systems, such as the Sämischand Averbakh variations.
The opening is classified in the Encyclopaedia of Chess Openings (ECO) with the codes A53–A55.
The Main line is 3. Nc3 e5 4. Nf3 Nbd7 5. e4; White can also play 4.dxe5 dxe5 5.Qxd8+, but despite the displacement of Black's king, this has long been known to offer no advantage, e.g. 5...Kxd8 6.Nf3 Nfd7!, with Black often following up with some combination of c6, Kd8–c7, a5, Na6 and f6. Black's position is solid and his piece coordination is good; White's pawn exchange in the center has allowed Black equal space and freed the f8-bishop. 5... Be7 6. Be2 0-0 7. 0-0 c6 8. Re1 (or 8.Be3) and White stands slightly better.
The Janowski Variation, 3. Nc3 Bf5, was first introduced by Dawid Janowski in the 1920s. The idea behind the variation is that 3...Bf5 prevents White from immediately grabbing space with 4.e4. The variation did not gain much popularity until the 1980s. Several top-level players have employed the line multiple times, includingMikhail Tal, Bent Larsen, Florin Gheorghiu, and Kamran Shirazi.
This is also reached by 2.Nf3 d6 3.c4. De Firmian suggests 3...Bg4. 3...c6 and 3...Bf5 are also possible. 3...g6 will likely transpose to the King's Indian Defence, and 3...Nbd7 4.Nc3 to the Main line.