The Stafford Gambit is an aggressive line for black in the Petrov Defense and begins with the moves:
1. e4 e5
2. Nf3 Nf6
3. Nxe5 Nc6
The accepted line continues with:
4. Nxc6 dxc6
Black is giving up a pawn to open up the center for both bishops and queen to freely attack. White will normally continue with d4, d3, or Nc3. All of these have many traps that white can fall into which makes this opening so dangerous.
With the e-pawn under attack it makes sense for white to push forward and attack the knight on f6. Black will now move Ne4 and attack the weakened f2 pawn. This is a tricky spot with many traps. If white tries to kick the knight away with d3 then white can play Bc5 with no good moves from white. If they take the knight then Bxf2+ and eventually the white queen will fall.
If instead white plays d4 to control the center, black can spring into action with Qh4. This sets another trap. Black is threatening Qxf2# but if white defends with g3 then black can take with Nxg3. If hxg3 then white loses the rook and if fxg3 then Qe4+ and forks the rook.
If white continues with Nc3 after 5…Ne4 then black will also play Qh4 putting maximum pressure on the king side.
This moves tries to solidify the pawn chain from white but it allows black to launch a strong attack with 5…Bc5. If white plays normally with a development move like Nc3 then it loses to Ng4 from black. The f2 square is under attack and there is no way to defend it.
If white continues with 6. Bg5 trying to pin down the knight then black can ignore the pin and play 6…Nxe4. If white takes the now vulnerable queen they will lose to checkmate. If they don’t, they are still in lots of trouble.
The last move you may see is 5. Nc3. It seems like a safe move and defends the pawn on e4. The issue is that black can still be very aggressive with Bc5. White can’t play normal center controlling moves such as 6. d4 because black can just take with 6…Bxd4. The knight on c3, which normally protects it, is gone.
If they try to get their light square bishop to e2 or c4 black can launch strong attacks on the king side with Qd4 or Ng4 respectively.
Hopefully you can start to see all of the traps that white can fall into in the Stafford Gambit. While black gives up material earlier, this opening has plenty of reason to try it out against your opponent.
Below you can watch all of the lines referenced on this page and see a much deeper analysis on the Stafford Gambit Accepted opening.