In some amateur sports leagues a game will be ended under the "mercy rule" if one team is significantly ahead of its opponent (i.e. unlikely to lose under normal circumstances). Such is not the case in chess - you can have a better position on the board for 18 moves, say, and resign after the 19th. As in the following game.
Wall, Bill - Guest757810
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+
4...Kxf7 5.Nxe5+ Nxe5 6.d4 Bxd4 7.Qxd4 d6 8.Nc3 Nf6 9.Bd2
There are 4 previous games in The Database with this move. White scored 0%. To be fair, all of the Jerome Gambiteers were playing higher-rated opponents.
9...Be6 10.O-O-O Qe7 11.f4 Nc6 12.Qf2 Bg4 13.Rde1 Rhe8 14.h3 Bd7 15.g4 Kg8 16.e5 dxe5 17.fxe5 Nxg4 18.hxg4 Bxg4 19.Rhg1 (19.e6!? =) 19...Qe6 20.Re4 Bf5 21.Rh4 Bg6 22.Bf4 Nxe5 23.Bxe5 Qxe5 24.Rhg4 Qe3+ 25.Qxe3 Rxe3 26.Nd5 Re2 27.Nxc7? Rxc2+ 28.Kd1 Rd8+ 29.Ke1 Rxc7 30.a3 Rc1+ 31.Kf2 Rxg1 32.Rxg1 Rd2+ 33.Ke3 Rxb2 34.Rg4 Rb3+ 35.Kd2 Rxa3 36.Rb4 b6 White resigned, HauntedKnight - Molepolole, FICS, 2014;
9...Bg4 10.f3 Be6 11.O-O-O a6 12.g4?! Nxf3 13.Qf2 Bxg4 14.h3 Bh5 15.Be3 Re8 16.Rd5?! Nxd5 17.Nxd5 Rxe4 18.h4 Rxh4 19.Rxh4 Qxh4 20.Qf1 Qe1+ 21.Qxe1 Nxe1 22.Nxc7 Rc8 23.Nd5 Re8 24.b3 Bf3 25.c4 Bxd5 26.Kd2 Nf3+ 27.Kd3 Bxc4+ 28.bxc4 Ne5+ 29.Kd4 Nxc4 30.Bc1 b5 31.Kd5 h5 32.Kc6 h4 33.Kb7 h3 34.Bf4 Re4 35.Bg3 g5 36.Kxa6 Re3 37.Bh2 Ra3+ 38.Kxb5 Rxa2 39.Kxc4 Rxh2 40.Kd5 Rg2 41.Kxd6 h2 42.Ke5 h1=Q 43.Kd4 Qe1 44.Kd3 Rd2+ 45.Kc3 Qc1+ 46.Kb3 Rb2+ White resigned, HauntedKnight - BalintM, FICS, 2014;
9...Re8 10.O-O-O Nc6 11.Qe3 Bf5 12.f3 Na5? 13.Qg5 Bxe4 14.Qxa5 Bc6 15.Qb4 a5 16.Qc4+ d5 17.Qh4 b5 18.Bg5 b4 19.Nb1?! (19.Ne4!?) 19...h6 20.Bxf6 Qxf6 21.Qh5+ Qg6 22.Qh3 Re2 23.Nd2 Qxg2? 24.Qf5+ Kg8 25. Rhg1 Qf2 26.Qf4? (26.Qg6!?) 26...Rf8?! (26...Rae8!?) 27.Qxh6 Qd4 (27...Qxg1 28.Rxg1 Re1+ 29.Rxe1 gxh6 =) 28.Nb3 (28.Qxc6 Rxd2 29.Qe6+ Kh8 30.Qh3+ Kg8 31.Rxg7+ Kxg7 32.Qg3+ Kh7 33.Rxd2) 28...Qf6 29.Qxf6 Rxf6 30.Nd4 Rxh2 31.Nxc6 Rxc6 32.Rxd5? Rcxc2+ 33.Kd1 Rxb2 34.Rxa5 Rb1 checkmate, HauntedKnight - makeclean, FICS, 2013; and
9...Rf8 10.O-O-O Kg8 11.f4 Nc6 12.Qf2 Ng4 13.Qf1 Qf6 14.h3 Nh6 15.g4 Nf7 16.Nd5 Qd8 17.Bc3 Be6 18.Ne3?! Ng5!? 19.Qd3 Rxf4 20.a3 Nxe4 21.Rdf1 Rxf1+ 22.Rxf1 Nxc3 23.Qxc3 Qg5 24.Kb1 Qc5 25.Qd2 Qd4 26.Qf2 Re8 27.c3 Qd3+ 28.Ka1 Na5 29.Nf5 Nb3+ Black resigned, Darthnik - rsnoob, FICS, 2011.
10.Qe3 Rf8 11.O-O-O Nc4 12.Qd3 Nxd2 13.Rxd2 Kg8
Black has castled-by-hand and has a piece for a pawn. If he keeps on making good moves, he will collect the full point.
14.e5 Ng4 15.exd6 Nxf2 16.Qd5+ Kh8 17.Re1 Bd7
Black has to keep his eye on White's pawn at d6, but with an extra piece for a pawn, he is doing well. Still, it is a complicated position. How should he continue?
Protecting the pawn at c5 and attacking the enemy Queen.
19.Qxb7 Black resigned
Wow! Black's Bishop is threatened, and the only square that even looks "safe" allows White's pawn to advance, 19...Be8 20.d7 Bf7 21.Qxa8!? Qxa8 22.d8/Q+ Qxd8 23.Rxd8+ Bg8 24.Ree8 - not so safe for the Bishop after all.
Best for Black seems to be giving up the Bishop for some play, 19...Qf8 20.Qxd7 Ng4, but after 21.Qe6 White will have centralized pieces and a couple of extra pawns, especially the dangerous on at d6.