Hey, sorry for that, such issue never been reported before. I will do my best to investigate. What browser are you using? Are sounds/music keep playing? Or game is frozen?
Chrome on Linux (Version 147.0.7727.137 (Official Build) (64-bit))
I do not generally play with sounds sorry. The black started at the top of the screen then slowly covered everything except the menus to the left of the screen, could still click on the temple thing (if could find it :D), that menu would show, but nothing else.