Spike Variation, Scorpion-Grob Gambit

The Scorpion-Grob Gambit arises when White, after 3. Nc3 dxe4, does not regain the pawn at once and instead plays 4. d3. The point is to challenge the e4-pawn and offer to open the d- and e-files, trading material for faster development. Black is a pawn ahead, and the advanced g-pawn still gives Black a target on the kingside. It is a seldom-played surprise line rather than an established system.