Englund Gambit

Black offers the e5 pawn straight away and races the queen to b4/b2 to grab material back or provoke a mistake, and bets that an unprepared White player mishandles the queenside. It's objectively dubious with best play - White keeps the extra pawn - but at club level it wins a lot of quick points because the traps are sharp and the correct defenses are obscure.

• The headline line is 4.Bf4 Qb4+ 5.Nbd2 Qxb2 6.Rb1 Qa3 - the natural knight move hands back the b-pawn and tangles the queenside, though quiet play (e3, Be2, castling) still leaves White the better side, so if you're Black, always check for Qb4+ hitting b2 and a loose bishop on the same rank before playing anything else.
• As White, the cleanest answer to Qb4+ is 5.Bd2 (not Nbd2), and after ...Qxb2 the move is 6.Nc3 - keep developing and let Rb1 and Nd5 chase the queen. Never 6.Bc3: 6...Bb4! wins the a1 rook, and 7.Qd2 Bxc3 8.Qxc3 walks into Qc1 mate.
• Watch for the Stockholm trick 3...Qe7 4.Qd5!? and forks c6 and f7 at once; Black equalizes the threat with 4...Nb4 and hits the queen and c2 rather than panicking and losing a piece.
• Both sides commonly misjudge the extra pawn: White should just finish development (Nc3, e3, Be2/Bf4) and hang onto e5 rather than chasing Black's queen around the board, while Black's compensation is piece activity and traps, not a guaranteed edge - don't play on hoping the gambit 'just works' if White defends accurately.
• If White declines with 2.d5 or 2.Nf3 instead of grabbing the pawn, Black should stop looking for gambit tricks and just develop normally (...Nf6, ...Bc5/...Bb4, ...d6) - trying to force sacrifice ideas against a sound setup only loses time.
• A frequent Black blunder is playing 3...Qe7 automatically without checking that 4.Nc3 or 4.Bf4 first defends everything, then discovering there's no real follow-up if White simply castles and returns the extra pawn with e3/Be2 - have a concrete plan (Qb4+ ideas or ...Nxe5 recapture) before committing the queen.