Thinking from the perspective of a modder... If we can make maps, we can make maps dark. If we can create scripts, we can force a certain time or event to trigger 'night,' aka a duplicate map of the original in dark form. This would be more akin to games where it's always day until you 'sleep.' It's not a realistic solution, but modders could certainly create this version.
I imagine, depending on how open the scripting engine is, we could create a night/day system from scratch. On certain events, check the time (or maybe the game is always listening for time). If it's between certain numbers, cause a recalc of alpha and color based on predefined settings. Might be jarring, and it would be fairly resource intensive. The benefit of a system like this in code is efficiency.
At the end of the day, though, I'm not sold it's necessary for a game like D:OS. Certainly it's a cool feature, but not one that would sell the game.
