The Scotch Gambit is effective at club level as Black will often get confused by the various transpositions and can easily end up in an inferior line of the Göring Gambit. There are various sources on this line, most notably Tim Harding's articles at his ChessCafe.com column, and Mark Morss covered some of the lines at his "Hard Chess" column. The Scotch Gambit was recommended in the book Chess Openings for White: Explained, although I don't recommend the book (see John Watson's review at http://www.chess.co.uk/twic/jwatsonbkrev77.html, which points out some serious issues). Another interesting source on these lines is Jude Acers and George Laven's Italian Gambit System and a Guiding Repertoire for White; the book's assessments are often over-optimistic for White but the analysis is pretty good.
1.e4 e5 2.d4 exd4 3.Nf3 Nc6 4.Bc4 (or 2.Nf3 Nc6 3.d4 exd4 4.Bc4)
Scotch Gambit coverage
Here I look at Black’s alternatives to 4...Bc5 and 4...Nf6, which give White chances of an edge, and in some cases White can get into good lines of the Göring Gambit. White is often faced with a key decision as to whether to offer a gambit with 5.c3, or to play 5.0-0 and only then 6.c3, or to recover the pawn with 5.Nxd4. In this section I also cover 4...Bc5 in conjunction with both sides’ alternatives to 5.c3 Nf6, but it seems probable that 5.c3 Nf6 represents best play by both sides.
This reaches a position that often arises via 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.c3 Nf6 5.d4 exd4. In this variation White can defer the capture on d4 with 6.0-0 or 6.e5, both of which offer reasonable practical chances and suffice for dynamic equality, or the less reliable 6.b4. Instead the main line continues 6.cxd4, whereupon White temporarily gets a strong centre but Black’s slight lead in development enables Black to counterattack against the centre and equalise. After 6.cxd4 Bb4+, White can choose between the relatively unexplored 7.Nbd2 (which provides White with compensation for a pawn), and the traditional main lines 7.Bd2 (solid, but can lead to very level situations) and 7.Nc3 (a tricky but dubious pawn sacrifice).
4...Nf6 transposes to the Two Knights Defence line 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.d4 exd4. 5.Ng5 may suffice for equality but it is not as reliable as 5.e5 or 5.0-0. I provide some coverage of 5.Ng5, but for a more extensive coverage I will refer the reader to Michael Goeller’s site at http://www.rci.rutgers.edu/~goeller/urusov/perreux/index.html. 5.e5 has become the most popular response at high levels, and often leads to interesting and unbalanced play, but Black has three good counters in 5...d5, 5...Ne4 and 5...Ng4, taking advantage of the fact that White has not castled yet.
With 5.0-0, White castles to safety and prepares to attack Black down the e-file. Many recent articles (e.g. Tim Harding’s Kibitzer column at Chesscafe.com) have been quite dismissive of 5.0-0, but Lev Gutman and Stefan Bücker have found various ideas that have revived these lines for White. Black’s most reliable counter is 5...Nxe4, which is best met by the visual tactical sequence 6.Re1 d5 7.Bxd5 Qxd5 8.Nc3, and White has ways to unabalance the play here, though Black has equality after either 8...Qa5 or 8...Qh5. Braver souls with Black can venture 5...Bc5, although the version of the Max Lange Attack with 6.e5 d5 7.exf6 dxc4 8.fxg7 Rg8 9.Re1+, followed by Bg5, gives White good prospects.