B00

Rat Defense: Fuller Gambit

Chess diagram: Rat Defense: Fuller Gambit after 3…Nf6

Type a move and press Enter: e4, Nf3, O-O, or from and to squares like g1f3 (e7e8q to promote). The board is also played with the mouse.

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Statistics from Lichess

3,271 games: White 47.0% / Draw 4.6% / Black 48.5%

The moves played next. Pick one to see it on the board.
Next moveGamesWhite / Draw / BlackW / D / B
1,0691,069
990990
571571
325325
154154
128128
1818
88

Rated Lichess games between players rated 1600 to 2500, from the Lichess opening explorer, updated Oct 30, 2026

Engine evaluation

+0.47 White is slightly better

Best play: 4. Nf3 Nxd5 5. d4 e6 6. a3 g6 7. c4 Ne7 8. Nc3 Bg7

Stockfish 19, depth 30, after the line's last move. Scores are in pawns, from White's side.

Overview

Rat Defense: Fuller Gambit (ECO B00, Semi-Open Games) is a gambit in the Rat Defense: Harmonist, reached after 1. e4 d6 2. f4 d5 3. exd5 Nf6 (3 moves).

In 3,271 rated Lichess games between players rated 1600 to 2500, White won 47.0%, Black 48.5% and 4.6% were drawn. White's most played move here is 4. c4, in 33% of those games.

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How to play against the Rat Defense: Fuller Gambit

4. d4 scores best for White: 52.2%, with White winning 49.8% and Black 45.5% of 325 games. The most played answer, 4. c4, scores lowest: 46.7% in 1,069 games. Stockfish's first choice is 4. Nf3.

Main answers: those played in at least 5% of these games. Score: White's wins plus half the draws, in rated Lichess games between players rated 1600 to 2500. How to play against other popular openings

Cite this page

Caissa Codex. “Rat Defense: Fuller Gambit (B00)”. Lichess data as of 30 Oct 2026. https://chesscodex.org/openings/rat-defense-fuller-gambit