Unfortunately long press didn't work for me with a trackpad (Safari on macOS), so wasn't able to flag at all. Maybe add a test for ctrl-click or shift-click?
Took me back to playing minesweeper as a kid. I managed to find myself in an end state that could only be resolved with a 50/50 guess. I don't remember if the classic version had this problem, but I think it would be nice to have a guarantee of no ambiguous boards.
Unfortunately long press didn't work for me with a trackpad (Safari on macOS), so wasn't able to flag at all. Maybe add a test for ctrl-click or shift-click?