Mikenas Defense: what should White play?

In the Mikenas Defense (ECO A40), White faces the unorthodox development of Black's queenside knight on move one. The engine's top-rated continuation is the direct space-gaining thrust d5 (eval +0.75), which confronts the knight immediately. Alternatively, White can choose classical development with Nf3 or c4, both of which are played far more frequently in recorded games.

The Direct Push with d5

Selecting d5 represents an ambitious attempt to punish Black's setup by taking territory in the center. Played in 16.9% of the 11,406,548 recorded games from this position, it earns White a 54.3% score. An illustrative engine continuation demonstrates how White establishes a broad center while Black relocates the attacked piece: d5 Ne5 Nc3 e6 e4 exd5.

Transposing to Classical Structures

The most popular response among human players is Nf3, appearing in 32.0% of recorded games (3.64M recorded) with a 55.4% score and an engine evaluation of +0.49. In the engine main line Nf3 d5 c4 e6 Nc3 Nf6, the game transitions cleanly into familiar Queen's Gambit territory. Similarly, c4 (eval +0.46) occurs in 30.5% of games (3.48M recorded), where c4 e6 Nf3 Bb4+ Nbd2 Nf6 allows White to contest central squares through standard English or Queen's Pawn structures.

Other Strategic Alternatives

White also possesses options to transpose into 1. e4 territory or adopt solid setups. The thrust e4 is chosen in 6.2% of games (711K recorded, eval +0.50), leading to lines such as e4 d5 e5 Bf5 c3 f6, which morph into Nimzowitsch Defense formations. Finally, the modest e3 (eval +0.40) accounts for 14.4% of games, illustrated by e3 e5 d5 Nb8 Nf3 d6, maintaining a solid pawn chain while quietly controlling central space.