Indian Defense: Accelerated London System: what should Black play?

In the Indian Defense: Accelerated London System, Black's most decisive and overwhelmingly preferred choice is Nxf4. By capturing White's unprotected dark-squared bishop on f4, Black immediately wins a minor piece, yielding a decisive engine evaluation of -3.40. Consequently, Nxf4 accounts for 99.4% of games in the database across 3.9K recorded encounters, with White managing to score only 29.2% from this juncture.

Winning Material with Nxf4

White has left the f4 entirely undefended, making Nxf4 the clear objective best move on the board. The capture removes an active piece and grants Black a substantial material advantage from the opening moves. The engine's illustrative continuation follows Nxf4 Qd2 Ne6 Nc3 d5 e4, demonstrating Black's ability to retain the extra material while calmly redeploying the knight to e6 to challenge White's central ambitions.

Passive Alternatives

Any move other than the immediate capture allows White to salvage the position and maintain a comfortable setup. For instance, g6 has been tried in 14 recorded games (0.4%), leading to an evaluation of +0.47 in White's favor, with White scoring 57.1% following lines like g6 Bd2 Bg7 e4 c5 dxc5. Other moves such as d5 (3 recorded games, +0.26 eval) and b6 (1 recorded game, +0.28 eval) both grant White an unhindered retreat for the bishop via d5 Bd2 Nf6 c4 e6 Nc3 or early initiative after b6 Qd2 Bb7 Nc3 e6 O-O-O. Ignoring the hanging piece with setups like c6 similarly surrenders the advantage, permitting c6 Bd2 Nf6 c4 d5 e3 with an evaluation of +0.47. Black should therefore execute Nxf4 without hesitation.