Thanks.
Only part of the map will take place at night though... In fact I want it to start out in the evening, then as far as the player progresses further in the level and gets to explore various sections of the city, night falls, weather changes, etc. and eventually a new day rises. Of course those scripted sequences imply a somewhat linear gameplay, but whatever. I don't think it's ever been done in a Duke map (I could be wrong though), and if things turn out the way I want them to turn out the results could be very, very atmospheric.