Allgaier Gambit (C39)

The Allgaier Gambit is a dangerous, but theoretically dubious, knight sacrifice that begins with 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.h4 g4 5.Ng5 (instead 5.Ne5 is the sounder and more conservative Kieseritzky Gambit). The knight on g5 has no safe retreat squares, and after 5…p, White plays 6.Nxf7 Kxf7, to...