Scotch Gambit, Dubois Réti Defense

The Dubois Réti Defense is the position after 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4. Black meets the Scotch Gambit by developing the king's knight before White has recovered the d4-pawn. The position is identical to the Open Variation of the Two Knights Defense, and from the Scotch move order it arises via 3. d4 exd4 4. Bc4 Nf6. Rather than guarding d4, the knight counterattacks e4, so White has to deal with that pawn as well as with winning back material.

Black is a pawn up, but the extra material comes with liabilities. The e5 square lets a white pawn advance with tempo against the knight. The knight on f6 can be pinned, and f7 is already in the sights of the c4-bishop. The pawn on d4 also leaves Black with doubled d-pawns. The engine rates the position as roughly balanced, and White has an unusually wide choice of fifth moves.

The most popular is 5. e5, the Advance Variation, sometimes called the modern treatment. It drives the knight away and usually leads to a central counterblow or to the Kingside Variation, 5...Ng4. Castling with 5. O-O is the classical approach. It invites 5...Nxe4, after which 6. Re1 d5 7. Bxd5 Qxd5 8. Nc3 is the Anderssen Attack, using the pin on the e-file and the attack on the queen to recover the piece. The Perreux Variation, 5. Ng5, is a direct strike at f7 that is regarded as misguided. The plain recapture 5. Nxd4 restores material at once and gives the least sharp play. In practice it is also White's weakest-scoring option.

The rarer tries promise less. 5. Bg5 pins the knight, but Black can soon break the pin, and White is left without an advantage. 5. Qe2 prepares e5, although the pawn can advance immediately anyway. 5. c3 is considered a mistake because of 5...Nxe4. Black then has ...d5 available and enough time to block any pin along the e-file before it becomes dangerous.

The play is forcing and tactical, and draws are rare in the online database. White scores slightly better than Black overall, a little over half the games, and Black's results are worst against 5. Ng5.