DrMAL: This is also one of my favorite games, clearly not for quality of resistance. It's fascinating how, based at minimum on seeing black's earlier weak moves, black counts on future mistakes by spurning quick advantage in favor of potential long term gains.
In particular after black's (latest) mistake 7...Qe7 (best was 7...Qf6) white does not play his obvious best 8.Qxb7 but instead opts for 8.Nc3 to capitalize on development along with obvious follow up 9.Bg5
The kibitzing around what black could do on move 9 is entertaining if not terribly enlightening. Personally, if I were one of "The Consultants" playing black I would suggest to the other that we overpower white and make him switch sides. Fisher's decision to comment on the hopelessness of black's position at this point seems most appropriate.
Analyzing with Rybka 4.1 gives at first 9...Qc7 as black's best but within a second or so the chosen move is 9...Na6 which makes better sense. While 9...Qc7 unpins its knight and allows its bishop to develop, 9...Na6 allows potentially faster castling and threatens Nc5 to attack white's queen.
It does not make sense to run Rybka for days here, as the move 9...Na6 is clearly best. For grins, here is its line when depth d=23 is finished:
[+1.05] d=23 9...Na6 10.Bxf6 gxf6 11.Bxa6 bxa6 12.Rd1 Qb4 13.Rd3 Bd6 14.Ke2 Ke7 15.Qxb4 Bxb4 16.Nd1 Rhd8 17.Ne3 Rab8 18.Rhd1 Rxd3 19.cxd3 a5 20.Rc1 Kd7 21.b3 (0:37:27) 280868kN
Since black is behind in development at move 9, the worst thing is to make an aggressive move to allow the position to be easily opened. This is precisely the sort of move black chooses with 9...b5 and any reasonably strong player with white would play the sac 10.Nxb5 in an instant based on intuition, calculation is not even needed. Rybka finds this move at d=1 within milliseconds as well.
Likewise, within milliseconds, Rybka found black's obvious best response 10...Qb4+ that was not played:
[+2.46] d=1 10...Qb4+ 11.Qxb4 Bxb4+ 12.c3 cxb5 13.Bxb5+ Ke7 14.cxb4 Rc8 15.f4 h6 16.Bh4 a6 17.Ba4 Kf8 18.OľO Nc6 19.Bxf6 gxf6 (0:00:00) 0kN
At this point, the game is over, white's attack plays itself starting with 11.Bxb5+ but black again made things more fun by not seeing its obvious response 11...Kd8 that a strong player would also immediately choose:
[+5.39] d=1 11...Kd8 12.OľOľO+ Kc8 13.Rd3 Qb4 14.Rc3+ Kb7 15.Qxf7+ Qe7 16.Qc4 Qc5 17.Bxf6 Qxc4 18.Bxc4 gxf6 19.Bd5+ Kb6 20.Bxa8 Bc5 21.Rd1 Na6 22.Bd5 Nc7 23.Rb3+ Ka5 24.Rf3 Rf8 25.Bc4 (0:00:00) 0kN
What turns an even funner game into a classic comes from black's propensity to consistently choose lessor moves to help white instead of the obvious:
[+6.35] d=1 12...Qc5 13.Bxf6 gxf6 14.Bxd7+ Ke7 15.Rd5 Rb8 16.Rxc5 Rxb3 17.axb3 Kxd7 18.Rd1+ Ke8 19.Rc8+ Ke7 20.Rc7+ Ke6 21.Rxa7 Rg8 22.Ra6+ Ke7 23.g3 Rg4 24.f3 Rg8 25.Kd2 Rg6 26.b4 Rh6 27.h4 Rg6 (0:00:00) 0kN
After 12...Rd8 white plays the obvious:
[+6.72] d=1 13.Rxd7 Nxd7 14.Bxe7 Bxe7 15.Rd1 OľO 16.Bxd7 Bc5 17.Qf3 Bd4 18.Bg4 g6 19.Qf6 (0:00:00) 0kN
and black again chooses a lessor move 13...Rxd7 instead of 13...Nxd7 whereupon white plays 14.Rd1 its obvious move.
At this stage, black has a few choices where 14...h6 and 14...a6 may appear to help but 14...Qb4 is clearly best because it unpins black's knight to defend its rook and attacks white's queen. True to form, black again chooses good move for white, 14...Qe6 and white replies with the obvious:
[+10.85] d=1 15.Bxd7+ Qxd7 16.Qb8+ Ke7 17.Qxe5+ Kd8 18.Rxd7+ (0:00:00) 0kN
Black again ignores its obvious move 15...Qxd7 in hope of not losing its queen, setting up a mate in two for white which, of course he sees.
[Mate in 2] d=1 16.Qb8+ Nxb8 17.Rd8# (0:00:00) 0kN
The game is a classic because of the difference in understanding between opponents through their play. Morphy plays as any strong player today would which, in his day, was unique. His opponents show that two heads may not be better than one.