While fighting the end boss, the player character was suddenly unable to damage the boss enemy and the boss enemy did not attack back any more. After running around and wasting the remaning munition, the player character stopped moving. Every other action could not be performed: Was unable to move, reload, shoot or use the ability. I could also not access the main menu, because all buttons were missing when pausing the game. The only thing the player could do was turning in the direction of the mouse.