Map question

[Shadowpillar]

I've been mucking around with writing a map manually.
I was wondering, what are all the possible options for textures?
I'm trying to make a map that will resemble dark aether from metroid prime 2.
My main question is, how do I alter the cloud texture in a way it will load for all clients?
If this isnt a feature yet, then can I suggest adding that in the next release so people can edit the look of their maps completely.
the map I wanna make will have a dark look to it.
Also, any way to make it think it's night time all the time?