You can reduce the number of new picture resources you need by using views to show changes between day and night for indoor rooms. Depending on the level of detail you want, pretty much the only way the difference between day and night is shown for indoor rooms is through things like windows. For the upcoming second demo release of Jen's Quest, I added a window to the dorm room. The dorm room is accessible both during the day and at night, so rather than creating two different picture resources just to show a minor difference like that, I created a view for the window, and two cels -- one for daytime and one for nighttime. Then I put them in the picture with an add.to.pic().
It's another matter if you want to include a great deal of lighting detail. Lighting is very different coming from the sun versus coming from light bulbs, candles, etc. But if (like me)you're not all that concerned with that kind of detail then you can shave at least 67 rooms off the number of new ones that you must have in order to implement night time in the game. And if 20 of the existing logics don't have associated pictures, then you only need about 80 more picture resources, which is within the 255 limit.
