C21: Danish gambit, Collijn defence

C21 Sub-variants:

• Centre game
  1. e4 e5 2. d4 exd4
• Centre game, Kieseritsky variation
  1. e4 e5 2. d4 exd4 3. Nf3 c5 4. Bc4 b5
• Halasz gambit
  1. e4 e5 2. d4 exd4 3. f4
• Danish gambit
  1. e4 e5 2. d4 exd4 3. c3
• Danish gambit, Collijn defence
  1. e4 e5 2. d4 exd4 3. c3 dxc3 4. Bc4 cxb2 5. Bxb2 Qe7
• Danish gambit, Schlechter defence
  1. e4 e5 2. d4 exd4 3. c3 dxc3 4. Bc4 cxb2 5. Bxb2 d5
• Danish gambit, Soerensen defence
  1. e4 e5 2. d4 exd4 3. c3 d5
• Centre game
  1. e4 e5 2. d4 exd4 3. Qxd4