The King Kong checkmate

https://www.chess.com/variants/spell-chess/game/54091210/46/1

[White "wolyn"]
[WhiteElo "1919"]
[Black "chessl96"]
[BlackElo "1452"]
[Result "0-1"]
[Termination "Checkmate"]

Can anyone explain to me why I lost that game?

wtf??????? i mean i think that persons cheating because black had no legal moves right? probably a KoTH issue

I think cheats he had no legal moves and it said u got mated? Look at this guy's profile pic it literally is a hacker!

I don't think it was cheating but that's just because I've never encountered anyone cheating. It would make sense if this were a bug caused by this specific variant because you put them into check with an unfreezing piece. It probably messed up triggering checkmate on their turn and so instead it just triggered it on the next move, causing you to lose instead.

Wow. First of all, this is caused by a jump bug, not a freeze. Notice carefully that black's counter went from 2 to 1, and he played jump@g5 f4, which is illegal, but it registered as checkmate, but the rating system gives the win to whoever made the last move instead of who checkmated. The code was coded this way because the developers never foresaw that such a bug can happen.

Very interesting bug!

I suspect that Chessisfunforme is right about the assumption of the code that the winner checkmates.

The jump spell is a bit buggy, since it makes the logic think that a piece does not exist, and lets the king move to an otherwise attacked square, but it is not the whole story.

I was able to reproduce the bug with a simpler game:
1. e4 h5
2. Ke2 g5
3. Kf3 e6
4. Qe1 Nc6
5. freeze@b2 Qd1 jump@a7 Ra3+
6. jump@g5 Kf4#

Note that this is not some "mate delay" bug because the before-last move is not checkmate (the rook can be captured). More interesting is the fact that the freeze's cooldown seems to plays part here. If in move 5 white did not use a freeze, the game would not end, unless black captures white:
...
5. Qd1 jump@a7 Ra3+
6. jump@g5 Kf4 [black's turn...]

someone make sure to write about this in the bug reports forum

Now I understand the mechanics of this checkmate:
1. Make sure your king is in check and the freeze spell is not available
2. Use the jump spell on that piece that allows your king to run away from the attacking piece into another mating net

Now this, after the pawn promotion problem? Chess.com has gotta fix a lot of bugs!