1.e4 e5 2.Nc3
The Vienna Game was analysed by a group of Viennese chess players in the middle of the 19th century and was often used in tournaments by Wilhelm Steinitz (1836-1900), Jacques Mieses (1865-1954) and Rudolf Spielmann (1883-1942).
White initially makes a useful developing move with 2.Nc3 which, unlike 2.Nf3, does not block the f-pawn. This gives their position on the kingside more flexibility. Black usually replies with 2...Nc6 or 2...Nf6, which offers White three different deployment plans:
a) Sharpening the game with 3.f2-f4
b) quiet development with Bc4 and d3. He adapts the further development to the black plan
c) Fianchetto of the king's bishop (g3, Bg2).
After 2...Nc6 3.f4 exf4 4.Nf3, plan a) results in a position from the accepted King's Gambit with the additional move pair Nc3/Nc6. The other knight move, 2...Nf6, prepares ...d5 and after 3.f4 d5 4.fxe5 Nxe4 leads to a position that was long regarded as the main play of the Vienna Game.
Theory sees no major problems for Black to equalise here.
Plan b) is possible after both knight moves. But beware: after 2...Nf6 3.Bc4 White must also be prepared for 3...Nxe4, after which 4.Qh5
is the prelude to a line that has been given the imaginative name Frankenstein-Dracula Variation due to its tactical intricacies.
Plan c), the Fianchetto Variation, is the modern treatment that Boris Spassky chose several times. After 2...Nf6 3.g3, 3...d5 can actively follow, but after 4.exd5 Nxd5 5.Bg2 White relies on the strong bishop g2.
The Vienna Game is well suited for club players because there is little current theory. It usually catches your opponent on the wrong foot because they are only prepared for Spanish and Italian. It is very flexible because you can play it aggressively like a King's Gambit or slowly and positionally if this style of play suits you better.