After 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 4. ... Bc5 is normally a forced win for Black. However there are players of the Black pieces who want chess to be more of a challenge than that, so alternative moves do exist. One rare move in this position is 4. ... Nxe4 Now the intent is pretty clear, in that Black is either hoping for 5.Nxe4 d5 or 5.Nxf7 when either 5. ... Qf6 or 5. ... Qh4 can be tricky. It also serves a a bit of a surprise weapon as often White knows there is something wrong with it, but they just can't remember what it is.
This seemed to be the case at the ANU Chess Club this evening when one of the games on the Winter Rapid began this way. White had a bit of a think, but eventually found the one sequence that gives White better chances. 5. ... Bxf7+ Ke7 6.Nxe4 (The sneaky 6.d3 has also been played here) 6. ... Kxf7 7.Qf3+ and even if Black does not fall for 7. ... Kg8?? 8.Ng5! then White should be fine.