Kloosterboer Gambit

The Kloosterboer Gambit is a sharpening of the Blackburne-Kloosterboer Gambit, 2...c6. After 3. dxc6, Black does not recapture with 3...Nxc6. Instead 3...e5 leaves the pawn on c6 and stakes a claim in the center, opening the diagonal of the f8-bishop and preparing quick development. Black is two pawns down and White's c-pawns are doubled. The c, d and e files are all half-open, and Black's compensation rests entirely on piece activity and on White's lagging development. Reference sources call the line dubious, and the engine gives White a clear advantage.

The most frequent reply by a wide margin is 4. cxb7, which takes a third pawn and removes the advanced pawn before it can be rounded up. 4. Nc3 and 4. Nf3 are more modest; they develop and return some of the initiative question to Black. The engine also rates 4. Bc4 highly. The gambit is almost unknown in master play. On Lichess, however, Black scores slightly better than White from this position, including after 4. cxb7, which suggests that in practice White is often unprepared.