heuristic: <e5 is bad>
well, 9...Nf6 is a rare line.
although 10.d5 Ne5 11.Nxe5 dxe5 12.Ba3 Nd7 is better,
10.e5 allows Morphy to post the blkB on the a3-h8 diagonal,
something he did in a few other games of this time (during the congress)
<clever Q sacrifice>
although 11...exd4 12.Re1+ Be6 13.Qb3 Na5 14.Bxe6 Nxb3 15.Bf5+ Qe7 16.Rxe7+
is a clever sequence, there are better moves in the tree.
13.Ng5 d3 14.Bxe6 Bxf2+ 15.Kxf2 Qd4+, 14.Bb5+ c6 15.Rxe6 Kd7
(15...fxe6 16.Qxe6+ Qe7 17.Qxe7#) 16.Rd6+ Kc8 17.Rxd8+ Rxd8 18.Qxf7 dxc3 19.Qxg7
it looks like 17.Nd5 should be considered another mistake.
17.Bxe7 Qxe7 18.Qg4 dxc3 19.Qxg7 or 17.Rad1 Qd7 18.Qxd7+ Kxd7 19.Rxd4+
are both stronger.
i've seen this in 2-4 games now. Morphy could have played the best move one move earilier.
21.R6e4 is interesting. 21.R6e4 c6 22.Rxd4 Kc8 doesn't look as strong as
21.R6e5 c6 22.Bd6 Nh6 23.Nf4 b6 and is still filled with tactical possibilities.
according to an engine, both players lost their way on move 34.
34.h4 b5 35.Rh6 Kb7 is not as strong as 34.Rg7 b5 35.Rxg6 a4 36.h4 Ka7
and 34...Rg8 is not as defensible as 34...b5 35.Rg7 b4 36.Rxg6 Kb7 37.h5 a4 38.Rd6 b3
it looks like WHT's strategy should be to push the g & h pawns and ignore its a pawn
and BLK's strategy should be to ignore its g pawn and push the a & b pawns!
I don't like 35...b5 because i would think the K needs to get more mobile. But
I don't know what the BLK K should do, either assist its pawn push or attempt to
stop WHT's pawn push? in this game, BLK loses because the R can not defend the R+P
i don't trust engine analysis when in the endgame, so i just work it out OTB....