What Rat Defense: Fuller Gambit puts on the board
White has a one-pawn material edge; white is to move.
White has central pawns on d5.
White can still castle either side; Black can still castle either side.
The d-file is half-open for Black, giving that side a natural pressure lane.
What White is trying to build
Develop around the Rat Defense pawn structure before starting a wing operation.
Use time and open lines as the compensation; recovering material is secondary.
How Black challenges it
Contest the centre and finish king safety before collecting loose material.
Improve the least active piece before committing the pawn structure.
The tactical pattern to recognise
Checks, forcing captures and development with tempo determine whether the offered material is justified.
Loose pieces and undefended central pawns matter more when both sides are still developing.
What to check before committing
Repeating a piece move without checking whether a new piece can be developed instead.
Accepting material without calculating the opponent’s forcing reply.
Choose the next book move
Preview a move to see the resulting position and the idea behind it. Select it to continue on the same board.