Is this a legal checkmate?

Perfectly legal. Most likely on the previous move the queen was on f6, the knight on g7, and the king on h8. The knight moved to e6, blocking the rook check and giving discovered check to the king.

Even though it's pinned, the knight is still considered a defender of the queen, since technically if you tried K takes Q, the K would still be moving into check. Maybe it's counter-intuitive, but them's the rules.
yes its legal,
simplify it imagine you had been put in check and you blocked the check with your knight, at the same time your knight put the opposing king in check.
Even though your knight is pinned - it still counts that you put the other king in check. That says even though the knight is pinned he still covers all the spaces he can reach. You cannot move your king into check.
You cant take the queen, the space is covered by the knight. Therefore its totally legal.

basically you want to take their king after they've taken yours, chess is a polite game, each player makes their move before you can move, so they would capture your king before you can take theirs. Funny thing about chess is that you never actually "take" the opposing king just check and mate because you can't escape.

Common question (and a legitimate one), and I understand the logic.
But it strikes me as funny too :) "They can't put their king in check, therefore I can put mine in check first"
But as you see, the rule applies to you both, and the queen cannot be taken ;)

yep, that's a legal CM. No problem. By definition, the King is directly attacked and can not take or block the Attacking Q or move to a safe square. It doesn't matter that the Knight is pinned.

To sum it up: The only relevant factors are that
1) Check is not dependent on the checking piece actually being able to move (to "take the king").
2) It is not allowed to move the king into check.
Is this a legal checkmate or did the system mess up? Notice the knight can't move because it would place the white king in check - does that still mean the black king can't take the queen?
well it would be a legal check because if the black king took the queen he would be checking himself so yes it is a legal check

Perfectly legal. Most likely on the previous move the queen was on f6, the knight on g7, and the king on h8. The knight moved to e6, blocking the rook check and giving discovered check to the king.
Actually the white knight was there first, then black moved his rook, then the white queen came down from g4, taking out a pawn in the process.

The computer will decide if this is legal.
Actually, if it would decide it's not checkmate, then we should decide it is badly programmed.


The best checkmates are those when you have three pieces working together and all of them are under attack.

Consider this:
Ignore the ideas of "check" and "checkmate". You simply lose when your king is dead. Now look at the board once again. If the black king captures the queen, the white knight captures the black king, winning the game immediately. It is true that black's rook can take white's king if given another move, but the battle is already over when the black king is slain.