The Vienna Gambit
The original idea behind the Vienna Game was to play a delayed King's Gambit with f4, but in recent play White often plays more quietly (for example by fianchettoing his king's bishop with g3 and Bg2). Black most often continues with 2...Nf6. The opening can also lead to the Frankenstein–Dracula Variation.
Weaver W. Adams famously claimed that the Vienna Game led to a forced win for White. Nick de Firmian concludes in the 15th edition of Modern Chess Openings, however, that the opening leads to equality with the best play by both sides. (Wikipedia)