1e4Nc6Nimzowitsch Defense2d4...2.Nf3Declined Variation2...d6Williams Variation3.d4Nf62...Nf63.e5Ng4El Columpio Defense4.d4d65.h3Nh62...e6Franco-Nimzowitsch Variation2...f5Lean Variation2...e5Transposition: C44 King's Knight Opening/Normal Variation. Avoid this move if you don't want a transposition to one of the more regular openings.2...d53.exd5Qxd54.Nc3Qa52...g63.d4Bg74.Nc3d65.h3Nf62.Nc32...g6Pirc Connection2...e6French Connection2...Nf63.d4e5Breyer Variation2...e5Transposition: C25 Vienna Game/Max Lange Defense2.Bb5Pseudo-Spanish Variation2.b4Wheeler GambitNxb43.d4d54.Ba34...Nc6?!5.Bb5dxe46.Bxc6+bxc67.f3?!4...e55.c3Nc66.Bxf8Kxf87.dxe5Nxe58.Qxd5Qxd59.exd5Nf610.c4Bf511.Nd2∓2.f4d52...e53.e53.exd53...Nh64.d4Bf53...d43...Bf52.b32...d5Scandinavian Variation. This is really the only good move here. All the other options are pretty bad for Black, so bad that I won't even cover them in this study. Do not allow White to play d5! It's that simple.2...d6?!⩲Mikenas Variation3.d5Nb84.c4Nf63.Nc3e54.d5Nce75.Bc4f56.f4fxe47.Nxe4Bf5±2...f6?±Neo-Mongoloid Defense3.Nf3e64.Bd3g65.d5Ne56.Nxe5fxe5±2...a6?!⩲Woodchuck Variation3.Nf3d54.exd5Qxd5±2...e6?!⩲3.Nf3f54.exf5Nf6Franco-Hiva Gambit 13.Nc3f54.exf5Nf6Franco-Hiva Gambit 23.c3d54.e5f65.Nf3Nge7⩲2...e5?!Kennedy Variation3.d5Kennedy Variation/Linksspringer Variation3.dxe53Nc3=...Scandinavian Variation/Bogoljubow Variation3.Be3⩱Hornung Gambit. Not good for White, but playable.dxe4Just take the pawn and have a good game.4.d5This gives White an interesting initiative in the center and a good lead in development. Still, it's questionable if this is compensation enough. The engine doesn't like it, but what does that mean in a Blitz game?Ne55.Nc3Nf66.Bd4Ng65.Qd4Ng45.Bb5+3.exd5Nb4Scandinavian Variation/Aachen Gambit3...Qxd5Scandinavian Variation/Exchange Variation4.Nc3Scandinavian Variation/Exchange Variation/Marshall Gambit3.e5Scandinavian Variation/Advance Variation. This is the line you'll most likely encounter in Blitz and Rapid games.Bf53...a64.c34.Nf3e65.c3f65.f4Nh66.Nf33...dxe43...a6Scandinavian Variation/Bogoljubow Variation/Brandics Gambit3...g6Scandinavian Variation/Bogoljubow Variation/Erben Gambit3...e5Scandinavian Variation/Bogoljubow Variation/Heinola-Deppe Gambit3...Nf6Scandinavian Variation/Bogoljubow Variation/Vehre Variation4d5Ne5Scandinavian Variation/Bogoljubow Variation/Nimzowitsch Gambit4...Nb85.f3Scandinavian Variation/Bogoljubow Variation/Richter Gambit5Bf4Ng66Bg3f5