1.d4 e5!? gives a pawn for quick piece play: ...Nc6, ...Qe7 and traps on the b-file and the e-file. Objectively risky, but full of pitfalls for an unprepared opponent. This is a beginner opening course for Black (ECO A40), written for players rated around 1000. Each move is explained and then drilled on a board; it is free.
Key ideas of Englund Gambit
After 2.dxe5 Nc6 3.Nf3 Qe7 the pawn on e5 is attacked twice and the queen eyes b4 and b2.
The famous trap: 4.Bf4? Qb4+ 5.Bd2 Qxb2 6.Bc3? Bb4!, and the a1 rook or mate on c1 follows.
Against careful play (Nc3, Qd5), win the e5 pawn back and develop quickly; do not hunt for tricks at any price.
The engine prefers White in most lines: your compensation is development and open lines, so keep the initiative.
The line trainer
The line trainer for Englund Gambit has 51 lines that grow out of 1. d4 e5, learned a few new ones a day with spaced-repetition review.
chessGM