DrMAL: In addition to providing basic lesson on importance of development, this game serves as great example of potential drawback to 4...Bb4+ subvariation in Scotch, main move is 4...Nf6 for equal double-edged game. With 4...Bb4+ black can keep extra pawn but white often gets bigger advantage from development. It is great historical example of strength behind gambit play, affecting opening theory. Staunton played modern way, valuing development, I think it is one of his best games.
6.Nxc3 was most popular move to simply develop N, but 6.O-O is generally considered better today, and 6.bxc3 is "newer" still (introduced here) also thought strong today. Here are computer starting lines (no opening book), in 6.bxc3 line moves O-O and e5 and Ba3 can all easily transpose. Eval score was +0.2 for 6.bxc3 and +0.1 for 6.O-O at intermediate depth.
Houdini_20_x64: 28/75 2:02:10 79,055,051,200
+0.02 6.bxc3 Ba5 7.0-0 Bb6 8.e5 Nge7 9.Ba3 0-0
0.00 6.0-0 Nf6 7.bxc3 Bc5 8.e5 d5 9.exf6 dxc4
-0.02 6.Nxc3 Nf6 7.e5 d5 8.exf6 dxc4 9.Qxd8+ Nxd8
After 6.bxc3 black is compelled to go 6...Ba5 other squares are not as good. For example, 6...Bc5 7.Bxf7+ Kxf7 8.Qd5+ and material becomes even but black K is out with big advantage white. With 6...Bd6 second best, d7 pawn (and LSB) is blocked.
7.e5 was sharp provocative move requiring accurate response 7...d5! or 7...Nge7! today this is known but response played back then 7...d6 was logical and could be expected from less prepared player. Staunton played 7.Qb3 best plan, threatening f7 pawn. Here 8...Be6 was most accurate but 8...Qe7 was also good.
From here Staunton played perfectly favoring development over material while black stumbled under pressure. 9...Nxe5 was correct, after 9...dxe5?! 10.Ba3! Qf6 (only move) 11.Nbd2! and white is down two pawns but has at least three pawns worth of compensation. Position is critical and 11...Nge7 was only move. After seemingly good 11...Bf5?! white's attack was crushing.