first guess is Bh2
How easy it is to make a mistake in 4pc | Weekly Puzzle December 27 2020.

PGN4
[GameNr "NONE"]
[TimeControl "1+15D"]
[Variant "Teams"]
[RuleVariants "EnPassant"]
[Red "blindFollowerOfTeammate"]
[RedElo "1828"]
[Blue "accidentalTrickster"]
[BlueElo "1902"]
[Yellow "mistakeMaker"]
[YellowElo "2150"]
[Green "ScaredResigner"]
[GreenElo "1917"]
[Result "1-0"]
[Termination "Green resigned. 1-0"]
[Site "www.chess.com/4-player-chess"]
[Date "Mon Dec 28 2020 05:11:14 GMT+0000 (Coordinated Universal Time)"]
[CurrentMove "24"]
1. h2-h3 .. b6-d6 .. h13-h11 .. Nn5-l6
2. Ne1-d3 .. b8-c8 .. Ne14-f12 .. m9-l9
3. Nd3-f4 .. b11-d11 .. Qh14-h13 .. Nl6-k4
4. j2-j3 .. Qa7-c9 .. Nf12xd11 .. m5-l5
5. j3xNk4 .. Ra11xNd11 .. Qh13-g12 .. Bn6xBi1
6. Nf4-d5 .. Rd11-a11 .. Qg12xc8+ .. R
Yellow makes the mistake Qxc8+ expecting a knight check. He missed this idea... Green to move (in this game they resigned) and turn this game into +7 and crushing position.
Enjoy and have a nice week.
we need to guess?
@puregut no need to guess you can solve it for yourself or guess if you like. I will post the solution in a month
.

@puregut no need to guess you can solve it for yourself or guess if you like. I will post the solution in a month .
ok!

qxc8 was the best move on the board, and resign was a perfectly reasonable move (i would of played on)

dont look at any blue pieces?????? what kind of puzzle exists where you should ignore 25% of the pieces lol

idk whether gts wants bh2 or qxi13 but both lose pretty easily. l7 (maybe k7 both the same idea but i would probably do l7) is the best but everything is losing. the puzzle is wrong

here's the mating sequel your welcome:
1. h2-h3 .. b6-d6 .. h13-h11 .. Nn5-l6
2. Ne1-d3 .. b8-c8 .. Ne14-f12 .. m9-l9
3. Nd3-f4 .. b11-d11 .. Qh14-h13 .. Nl6-k4
4. j2-j3 .. Qa7-c9 .. Nf12xd11 .. m5-l5
5. j3xNk4 .. Ra11xNd11 .. Qh13-g12 .. Bn6xBi1
6. Nf4-d5 .. Rd11-a11 .. Qg12xc8+ .. Bi1-h2
7. Nd5-b6+ .. Ka8-a7 .. Qc8xQc9+ .. Bh2xQg1
8. Nb6-c8+ .. Ka7-a8 .. Kg14-h13 .. Kn7-n6
9. Nc8-b6+ .. #

ill give credit where its due though: if this puzzle actually worked then all these players usernames would be the greatest ever, as blue accidentally tricked yellow, yellow made a mistake, green resigned because he was unnecessarily scared, and red just did whatever mistake yellow told him blindly. now i am rooting for these 4 players to play again and have this happen.
PGN4
[GameNr "NONE"]
[TimeControl "1+15D"]
[Variant "Teams"]
[RuleVariants "EnPassant"]
[Red "blindFollowerOfTeammate"]
[RedElo "1828"]
[Blue "accidentalTrickster"]
[BlueElo "1902"]
[Yellow "mistakeMaker"]
[YellowElo "2150"]
[Green "ScaredResigner"]
[GreenElo "1917"]
[Result "1-0"]
[Termination "Green resigned. 1-0"]
[Site "www.chess.com/4-player-chess"]
[Date "Mon Dec 28 2020 05:11:14 GMT+0000 (Coordinated Universal Time)"]
[CurrentMove "24"]
1. h2-h3 .. b6-d6 .. h13-h11 .. Nn5-l6
2. Ne1-d3 .. b8-c8 .. Ne14-f12 .. m9-l9
3. Nd3-f4 .. b11-d11 .. Qh14-h13 .. Nl6-k4
4. j2-j3 .. Qa7-c9 .. Nf12xd11 .. m5-l5
5. j3xNk4 .. Ra11xNd11 .. Qh13-g12 .. Bn6xBi1
6. Nf4-d5 .. Rd11-a11 .. Qg12xc8+ .. R
Yellow makes the mistake Qxc8+ expecting a knight check. He missed this idea... Green to move (in this game they resigned) and turn this game into +7 and crushing position.
Enjoy and have a nice week.