app or human mistake?

dario932
https://photos.app.goo.gl/Ld2hSttnqGxcFe566 ... my opponent won by moving Ng4.. Is It the app mistaken or Is there an explanation for It?? I didn't understand It..
K_Simonson
dario932 wrote:
https://photos.app.goo.gl/Ld2hSttnqGxcFe566 ... my opponent won by moving Ng4.. Is It the app mistaken or Is there an explanation for It?? I didn't understand It..

 

Your opponent moved their knight and revealed an attack on your king by their rook. This is called a discovered check and you had nowhere to move your king after this move, so it's checkmate.

Strangemover

Strangemover

That is checkmate by the Rh8. Kg2 is not possible because of the Qd2, Kxg4 is not possible because of the f5 pawn, white has no pieces which can block.