Chess Openings Lab
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Caro-Kann Defense: Alien Gambit

The Alien Gambit is 5.Ng5 h6 6.Nxf7, a knight sacrifice on f7 after Black's ...h6 kicks the knight. White gives a full piece for one pawn and an exposed black king, while Black wants to take the knight, tuck the king away and convert the extra material.

Moves
1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nf6 5.Ng5 h6 6.Nxf7
ECO
B15
Engine
−2.04 · a large advantage for Black (Stockfish 17.1, depth 20)
Played
602 games in our lichess sample
White scores
58.2%

Key ideas for both sides

White

  • After ...Kxf7, check at once with Bc4+ so the king cannot settle, then bring the queen to e2 to pin anything on the e-file.
  • Develop with Nf3, Be3 and long castling, hoping to open the center before Black untangles the kingside pieces.
  • Aim the knight at e5 with check ideas against a king on f7 or g8, where the f-file is already open.

Black

  • Take the knight with 6...Kxf7. Every other move leaves White with real threats and gives back the material edge.
  • Strike the center with ...c5, then shield the king with ...e6 so the Bc4 check meets a solid wall.
  • Finish development with ...Nc6 and a bishop to d6 or e7, then walk the king to g8 and connect the rooks.
  • Trade pieces whenever you can. Each exchange takes attacking power away from the side that is a piece down.

Plans and pawn structure

After 6...Kxf7 Black has knight against pawn, but the king stands on f7 with the f-pawn gone and the h-pawn already on h6. White's only hope is speed: Nf3, Bc4+, Qe2 and long castling, then a break in the center to open files toward f7. Black's plan is simple and strong: ...c5 to fight for d4, ...e6 to block the a2-g8 diagonal, ...Nc6, a bishop out, and then king to g8 with the rook joining on the f-file. Once Black's position is coordinated, the extra piece decides.

Where the engine's main line heads: White pawn d4, no e-pawns for White, no d-pawn for Black. White has a pawn on d4 and no e-pawn; Black has no d-pawn. White has more central space; Black's pieces are free and the d4 pawn is a target.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position −2.04: a large advantage for Black. Its three top choices for Black:

  1. −2.04 6...Kxf7 7.Nf3 c5 8.Bc4+ e6 9.Qe2
  2. +3.40 6...Bg4 7.Qxg4 Qa5+ 8.Bd2 Nxg4 9.Bxa5
  3. +4.74 6...Qd5 7.Nxh8 g5 8.Ng6 Qe4+ 9.Be2

Pawns, from White's side.

How it scores on lichess

602 rated lichess games reached this position; White scored 58.2%.

1200–159959.8%
1600–199959.4%
2000 and up54.1%

Light: White wins. Grey: draws. Dark: Black wins. About the sample.

How to play against it

As Black, take on f7 with the king and do not try to save material elsewhere: the second and third engine lines show how bad ...Bg4 or ...Qd5 turn out. Then play ...c5 and ...e6 before anything fancy. Do not grab more pawns while your king is still on f7. Develop, castle by hand to g8 and trade queens if White offers.

Questions

What are the moves of the Caro-Kann Defense: Alien Gambit?

The Caro-Kann Defense: Alien Gambit starts 1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nf6 5.Ng5 h6 6.Nxf7. Its ECO code is B15.

Is the Caro-Kann Defense: Alien Gambit good for White?

Stockfish 17.1 rates the position −2.04 at depth 20, which is a large advantage for Black. In 602 lichess games from our sample, White scored 58.2%. A dubious shock weapon for White that scores well against unprepared players, but a Black player who knows to take, play ...c5 and ...e6 should win.

What is the main idea of the Caro-Kann Defense: Alien Gambit?

White sacrifices a knight on f7 to drag Black's king into the open. The idea is to win with fast development and checks on the a2-g8 diagonal. With accurate play Black keeps the extra piece, so the gambit is objectively unsound.

What should Black play next?

The engine's first choice is Kxf7, with Bg4 and Qd5 close behind. 6...Kxf7 simply takes the piece, and the line 7.Nf3 c5 8.Bc4+ e6 shows Black blocking the check and staying a piece up.

Updated October 2026. Sources and method.