O'Kelly Variation, Venice System, Steiner Line

The Steiner Line is the most restrained of Black's answers to the Venice System. Instead of challenging the center at once with 3...d5 or preparing that break with 3...e6, Black plays 3...d6 and allows White to set up a broad pawn center with d4. The small pawn step keeps e5 under watch and keeps Black's position compact. Combined with the early ...a6, however, it leaves Black with less space, which is the main concession of the line.

White nearly always continues 4. d4, by a wide margin the most popular reply; 4. Bc4 and 4. Be2 are occasional alternatives. After 4. d4 the standard response is 4...Qc7. The queen leaves the d-file, so the d6-pawn is no longer pinned and an exchange with dxc5 can be answered by ...Qxc5. Black then fianchettoes the king's bishop and accepts a cramped but sound position, looking for counterplay against White's center later. The engine gives White a slight edge, and in online games White scores marginally better than Black.