411 REFERENCE · Wikibooks
Chess Opening Theory/1. d4/1...d5/2. Nc3/2...Nf6/3. Nf3/3...Nc6/4. e4
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4. e4?! — Reverse Arctic Gambit
After 1. d4 d5 2. Nc3 Nf6 3. Nf3 Nc6, White plays 4. e4?!, sacrificing the e-pawn to gain activity and force Black's knight to move.
4...Nxe4 accepts the pawn sacrifice, with Black's knight capturing the e5-pawn.
4...dxe4 accepts the pawn sacrifice,also the best move
Downsides: The main problem with 4. e4?! is that White deliberately offers the e-pawn before completing development. If Black can safely capture it, White may simply be left a pawn down.
Loses By -0.9 (?!)
(not a real opening name)