Bycote: Many of the games in Irving Chernev's book "The Most Instructive Games of Chess Ever Played" take well over 40 or 50 moves for the winning player to finally crown his victory. That doesn't mean the winner was underestimating his opponent's skill or playing at anything less than a genius level himself. It just means that's how long it took to win the game, that's it.
It is not a sign of weakness by the players in Chernev's book who take over 50 moves to win their games, rather it is a sign of *immense* strength that they are able to do so with such ease, and with what little advantage their opponents give them, as I believe Tiviakov does here. By move 40, black is utterly crushed and is only pretending to have any compensation at all for his piece, the real beauty and skill in this game is seen well before that point.
Tiviakov's play is a wonderful example, the best I know of in the Hanham opening, of how to take advantage of a weak opening to gain a superior position which can be converted into a material advantage and finally a win. In Tiviakov's place, a lesser player might choose moves like 9.Bxg5?, 11.Nc3/Nd2?, 12.Bb3/d3?, etc, any one of which would spoil the overwhelming position white obtained in the game. Tiviakov's play in this game is very instructive and very well-worth studying!
Some notes on the game:
After 15.c4! if black tries 15...a6, white follows with 16.Be3 O-O 17.b3! preparing a4 with an absolutely overwhelming position.
27.Ke3?? makes no sense and must be a typographical error. Either Bc2 (not e2) was played before this, or white played Ra3, then Ke3.
35.c5+! is a very accurate move by Tiviakov. Best for black is then 35...Kxc5 36.Ra5+ Kb4 37.Rxe5 Bxd1 38.Nxd1 hxg3 39.Kxd4 Rd8+ 40.Ke3 Rxd1 41.Re6 Rc1 when white has a winning rook-pawn endgame.
35...Ke7?? just drops the bishop as Tiviakov demonstrates, there's not much to comment on after that.