Rasa-Studier Gambit

The Rasa-Studier Gambit departs from the main lines of the Caro-Kann Defense at move four. Instead of recapturing with 4. Nxe4, White strikes at the e4-pawn with 4. f3, so that after 4...exf3 5. Nxf3 the king's knight comes into play with gain of time and the f-file is opened. White is a pawn down but has a lead in development and an open game, and the positions closely resemble the Blackmar-Diemer Gambit, into which several lines transpose. The Von Hennig Gambit, 4. Bc4, follows the same plan and often merges with it after 4...Nf6 5. f3 exf3 6. Nxf3.

Accepting with 4...exf3 is the most common reply and is also the engine's preference. Declining with 4...Nf6 is the main alternative and leads to the O'Kelly Defense of the Blackmar-Diemer Gambit Declined, while 4...Bf5 is seen less often. Engines give Black a slight edge, consistent with the view that White's compensation is incomplete, but the play is sharp, and White scores well in online games.