2...Qxd5 (Mieses-Kotroc Variation)

The idea

After 2.exd5 Qxd5 3.Nc3, the queen on d5 is attacked and Black chooses where to put it. 3...Qa5 is the main line and the most popular; 3...Qd6 and 3...Qd8 are the main alternatives. Lichess calls 2...Qxd5 the Mieses-Kotroc Variation.

Plans for White

Develop with tempo and build a center with d4 and Nf3. Bc4 or Bd2, castling and a timely Nd5 or Ne4 against the queen are all part of White's play. White's lead in development is small but real, and the plan is to keep adding to it.

Plans for Black

Put the queen on a square where it is out of the way, then follow up with ...Nf6, a bishop to f5 or g4, ...c6 and ...e6. Black's game is about finishing development without allowing White to gain more time against the queen.

Watch out for

For Black, other queen moves. Wikipedia calls them inferior: after 3...Qe6+ 4.Be2 Qg6 5.Nf3 Qxg2 6.Rg1 Qh3 7.d4, White's lead in development far outweighs Black's extra pawn.

For White, chasing the queen for its own sake. Each attack on it should also develop a piece or claim the center.