Chess Opening Theory/1. e4/1...e5/2. d3

This insipid move is playable but concedes White's first move advantage.

Inferior to most other responses to 1. e4 e5, 2. d3 defends e4, though it was not under attack. While it opens a line for the queen's side bishop to develop, it closes the line 1. e4 opened for the king's bishop. Should White wish to play d4 in the future, they have lost a tempo here. White misses the opportunity to develop a piece to make an unnecessary pawn move instead.

Black is allowed easy equality with 2...Nc6 or 2...Nf6 followed by 3...d5. This can lead to a position like a Philidor defence with colours reversed: e.g. 2...Nf6 3. Nf3 Nc6 4. Be2 d5 5. Nbd2⩱ is the reversed Hanham variation.

If White doesn't want to develop their king's bishop to e2 behind the pawn chain, their intention may to be to play in the manner of a King's Indian attack, where White builds a d3 and e4 pawn chain and the fianchettos the bishop to g2: though the move order 1. Nf3 (preventing e5) d5 2. g3 is more accurate.

There are also plans involving an early f4, a sort of inferior Vienna gambit, which are still equal but less popular.

1. e4 e5 2. d3