The Evans Gambit is a complex line with numerous options along the way for both sides, so it will probably take quite a while to complete the coverage. However, I feel that a site devoted primarily to romantic-style gambits would be incomplete without covering the Evans Gambit, which was especially popular at high levels of play during the late 19th century and is still played occasionally by grandmasters today, such as Nigel Short and Alexander Morozevich. I also had a lot of success on the white side of the Evans during my junior chess playing days. In some variations White can take advantage of the missing b-pawn by playing Bc1-a3 and catching the black king in the centre.
Black most often accepts the gambit with 4...Bxb4 (although the declined variation with 4...Bb6 is also important), whereupon White usually continues with the immediate 5.c3, attacking the black bishop. Instead 5.0-0 is less convincing because Black can play 5...Nf6 and strive for rapid castling, something that Black often doesn't get time for in the lines following 5.c3 without making concessions.
5...Bd6 is an unusual but fairly respectable move, reinforcing the pawn on e5. The main problem with it is that Black blocks in the c8-bishop by blocking the movement of the pawn on d7, and this often leads to Black getting into a tangle in the early middlegame. The usual continuation is 6.d4 Nf6 7.0-0 0-0 8.Re1, and then Black can try 8...h6 (preventing the plan of Nf3-g5 followed by f2-f4) 9.Nbd2 Re8,
whereupon White is doing quite well after both 10.Qb3 (attacking f7) and 10.Bd3 (getting the bishop out of the way of any ...Nc6-a5 tricks). Note that after 10.Bd3, Tim Harding's recommendation 10...Bf8 11.Nxe5 Nxe5 12.dxe5 Rxe5 13.f4 is flawed because of 13...Bc5+ followed by 14...Rh5, so White should prefer 13.Nf3.
The 8...Qe7 used in the main illustrative game Berelowitsch-Andersen, Bundesliga 2014 is less convincing because White plays 9.Nbd2 and if 9...Re8 10.Nf1 (preparing Ng5 followed by f4) and Black has serious problems maintaining the strong-point on e5.
This is a more important response which is often used by grandmasters, as it offers Black good scope to return the gambit pawn and reach equality (or at least get very close to equality), whereas the more critical 5...Ba5 makes it easier for White to insist on playing for compensation for a pawn.
An old favourite of Tim Harding's is 6.Qb3!? which attacks the f7-pawn immediately. Although Black can get in the ...Na5 fork (of the queen on b3 and bishop on c4) White can force concessions in the black kingside by playing 6...Nh6 7.d4 Na5 8.Qb5 Nxc4 9.Bxh6.
This line offers good practical chances, but be warned: objectively, I think it is flawed, because Black can play 9...gxh6 here and then follow up with ...Rg8, taking charge of the half-open g-file. For example, 10.Qxc4 exd4 11.cxd4 Rg8 12.0-0 d5! 13.exd5 Bh3, as played in Asker-Tosti, Brazil 1998. My main illustrative example is Morozevich-Bacrot, Sarajevo 2000, in which Black instead played 9...Nd6 and got equality.
More reliable is thus the main line with 6.d4 Na5 and then the traditional main line runs 7.Nxe5 Nxc4 8.Nxc4 d5 9.exd5 Qxd5 10.Ne3, where White has the better central control but Black has the bishop-pair. Since this line is probably no better than equal for White, most grandmasters have experimented with alternatives in the last two decades. Garry Kasparov tried 7.Be2 instead in the 1990s, whereupon Black should probably defend e5 with 7...d6 rather than allowing 7...exd4 8.Qxd4.
Nowadays most grandmasters, including Nigel Short, prefer 7.Bd3, which leads to roughly equal play after 7...d6 8.dxe5 dxe5 9.Nxe5. The game Short-Bruzon Batista, Poikovsky Karpov 2012, then continued 9...Nf6 10.0-0 0-0 11.Qc2 c5.
Short now played 12.f4, which allowed Black to generate counterplay on the queenside with 12...c4 and Black soon got the upper hand. I think that 12.Nd2 is probably best, covering the c4-square, and only then 13.f4, after which I slightly prefer White's position.
Another enhancement to my chess site is the addition of a brief section detailing some repertoire/move-order issues that players of these lines might come across (these will gradually be established across the site as I add new articles and update old ones). This was inspired partly by reading through some debates on the Evans Gambit at the Chesspublishing.com forum, where some members pointed out that a significant issue with the Evans Gambit is that White has to be prepared to face the Two Knights Defence (3...Nf6), which is also the main reason why I rarely face the Evans Gambit from the black side.
From White's point of view I would recommend either 4.Ng5 or 4.d4, depending on taste (the line 4.d4 exd4 is covered on my site via the Scotch Gambit), since 4.d3 tends to lead to relatively closed, slow games (especially if Black goes for solid defence rather than the more aggressive set-ups based on ...d7-d5 and/or ...f7-f5) and the Boden-Kieseritzky Gambit is currently looking somewhat dubious.