The Halloween Gambit, Plasma Variation is a variation of the Four Knights Game, catalogued as ECO C47. The line runs 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4 Nc6 6. d5 Ne5 7. f4 Ng6 8. e5 Ng8 9. d6 cxd6 10. exd6 Qf6 11. Nb5 Rb8, reaching the position shown below after 22 half-moves.
The four central squares are empty of pawns, so the fight for them is being conducted by pieces. Development is level at two minor pieces each, and Black is up two points of material. It is White to move after 11 moves. Black’s d-file pawn is isolated; the e-file file is fully open.
On the Four Knights Game generally: A symmetrical opening leading to equal but interesting positions. Good for beginners.
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The Halloween Gambit, Plasma Variation goes 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4 Nc6 6. d5 Ne5 7. f4 Ng6 8. e5 Ng8 9. d6 cxd6 10. exd6 Qf6 11. Nb5 Rb8. It is a variation of the Four Knights Game and is catalogued as ECO C47.
The Halloween Gambit, Plasma Variation is ECO C47. ECO codes group openings by their move order, so nearby codes cover closely related lines of the Four Knights Game.
Stockfish evaluates the position after 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4 Nc6 6. d5 Ne5 7. f4 Ng6 8. e5 Ng8 9. d6 cxd6 10. exd6 Qf6 11. Nb5 Rb8 at +1.51 at depth 18, which is a clear advantage for White. Engine evaluation is only a starting point — at club level the practical value of a line is mostly about whether you know its plans better than your opponent does.
The four central squares are empty of pawns, so the fight for them is being conducted by pieces. Development is level at two minor pieces each, and Black is up two points of material. It is White to move. Black’s d-file pawn is isolated; the e-file file is fully open.