The Krejcik Gambit 2.Bc4 Nxe4 3.Bxf7+

After 2.Bc4 Nxe4 3.Bxf7+ White regains the knight with Qh5+ and Qd5+: material is level again, but Black builds a strong centre with ...e6 and ...d5.

1.e4 Nf6 2.Bc4 Nxe4 3.Bxf7+ Kxf7 4.Qh5+ g6 5.Qd5+ e6 6.Qxe4 d5

Move by move

1.e4 – White occupies the centre and opens diagonals for the queen and the f1-bishop.
1...Nf6 – The Alekhine Defence: the knight attacks e4 and invites the pawn forward, planning to attack the advanced white pawns later.
2.Bc4 – White develops the bishop and leaves e4 undefended, with a blow on f7 in mind.
2...Nxe4 – Black takes the central pawn: a sound capture, but you must know what follows.
3.Bxf7+ – The Krejcik Gambit: White gives the bishop to draw the king out and then win back the e4-knight with queen checks.
3...Kxf7 – The king takes the bishop: castling is lost, but Black is a piece up for the moment.
4.Qh5+ – A queen check: it prepares Qd5+ to attack the king and the e4-knight together.
4...g6 – Black blocks the check with a pawn, driving the queen off h5.
5.Qd5+ – A check that also hits the e4-knight: White regains the piece.
5...e6 – Black blocks the check and, freeing the f8-bishop, builds a centre: the e4-knight is lost.
6.Qxe4 – The queen takes the knight: material is level, but Black has the bishop pair and the centre.
6...d5 – Black gains time on the queen and builds the e6-d5 centre: the king on f7 is safe behind the pawns.

Level material: Black has the bishop pair and the d5-e6 centre, White has an exposed queen and development still to complete.

The white queen must move again: Black continues with ...Bd6, ...Nc6 and ...e5, gaining more time.
The king steps to g7 and the h8-rook goes to f8: with the f-file open the black rook becomes active.
Push ...e5 to take the whole centre and open the diagonals for the bishops.