We recently had an interesting game end and we were unsure how to resolve it. Here is what happened as players moved very quickly at the end of both players time:
Player A made a move which was checkmate, but neither player saw it immediately
Player B made an illegal king move, as it was covered by a bishop on the far side of the board
Player A ran out of time
Player B called time
Player A saw the illegal move, called the illegal move, and backtracking the move called the checkmate
How is this resolved? Two other facts that matter:
1. The first person to point out the bishop attacking the king was not in the game.
2. Player Bs partner was also out of time when time was called, thereby making that time call a draw if it is in fact the standing result.
However, it is still unclear whether the MOVE that made checkmate supersedes subsequent time calls, or whether it is the ANNOUNCEMENT of checkmate.
Bughouse is played by the rules of Blitz Chess (i.e., five-minute chess), so there is no check or checkmate. The objective is to take the opponent's king before you run out of time. So in this game, Player B wins because s/he noticed that A had run out of time.
As in any chess game, bystanders have to be quiet until it's over.
First of all, Brian is absolutely wrong. There is checkmate in blitz chess, and it ends the game immediately. Capturing an opponent's king is equated to calling out an illegal move, it is NOT the "goal" of blitz.
Now with that out of the way, I have played lots of otb bughouse as well as blitz. Its a debatable situation, but I think it should be a draw with all fairness in mind.
The main factors to consider are:
1) There is a checkmate on the board.
2) Player A had run out of time before declaring checkmate, but before Player B called his flag.
In order to show that there was time left on the clock, it is Player A's responsibility to stop the clock when checkmate is declared. If there was no time left, the game is drawn. I believe this is also now the way USCF handles rated blitz games.
So, we actually stop the clock on the board in question when declaring checkmate. Not just to reset for the next game, but to "prove" that there was sufficient time left for the checkmating player. Of course, if you stop the clock in error, you will lose the game!
Had Player B called the flag first before the checkmate was seen, then it is debatable that Player B should win due to Player A's move not being "complete" (since he didn't yet see that it was checkmate on the board). It probably would go something like this:
Player B: "Flag!"
Player A: "Hey, I didn't see that it's checkmate!"
Player B: "Okay, it's a draw then."