My number one recommendaiton would be, if you can, calibrate brightness at game start. normally, I find the "adjust brightness until the center image is barely visible" step annoying boilerplate, but I think for a game like this, it's essential. On the level in quesiton, for instance, I could see absolutely nothing without flashes, no box, no button, just pitch blackness, on my monitor anyway. But your game's vibes are still pretty much immaculate, IMHO, which counts for a lot.