Scotch Opening

The Scotch Opening', or Scotch Game, is the following:

1. e4 e5
2. Nf3 Nc6
3. d4

The response by Black is typically 4.exd4.

The goal of this opening is to occupy the center of the Board, and to catch the opening off guard.

Defenses

4. Nxd4 (Main line)
4. ... Bc5 (Classical Variation)
4. ... Bc4 (Scotch Gambit)
4. ... Nf6 (Schmidt Variation)
4. ... Qh4!? (Steinitz Variation)
4. c3 (Göring Gambit)

Additional possibilities

4. ... Nxd4?!
4. ... Bb4+?!
4. ... Qf6