I mean nightc cycle = perma stealth = perma sneak attacks?
I wouldnt see it so extreme ...
I mean night only means lack of sunlight, aka the same situation as there is in the Underdark, or inside of buildings ...
I think they would either make it so moonlight would cancel stealth, just as sun do, or every guard would be holding a torch and roads would be full of them aswell.
I gues it would make ranged SA feel easier ... but since you only need to step out of vision cone, and you can hide on plain sight in the middle of day ... it would be only feeling.
