So my biggest problem is that I do not know what is in this theme pack that I am using. I have some options, though:
In my map, I can have the aliens just arriving. We don't want them on our Earth! Let's blow them up somehow! YEAH! [Aside, I see no logical way for two teams fighting one another to do this - the money reasoning of Frozen's is like a way for him to get out of having to explain other issues]. We would need assets that include a mothership and maybe smaller ships, and a couple things here or there, but for the most part, not much else.
--This would be basically a normal contest. Yay, I guess. But it would seem like a lot of effort and hype was put forth for nothing.
In my map, I can have the aliens having countered us for a long time (or hidden for a long time). They've established a sort of base on Earth. We don't want them on our Earth! Let's blow them up somehow! YEAH! [Aside, I see no logical way for two teams fighting one another to do this - the money reasoning of Frozen's is like a way for him to get out of having to explain other issues]. We would need assets for a spytech-like base, but with an alien theme (consoles, crates, barrels, etc.). Except, I don't know what I'll be provided with. Consoles, crates, barrels, etc. are common props used in alphas to help players get a sense of the environment that has yet to be put in there, and to help the mapper develop the map. It's not detail, but it's basically needed in an alpha. I can't just put normal consoles, crates, and barrels there - the scale may be different: I may put two consoles here and have a small path next to it, but the alien console might be bigger by what the modeller thinks isn't too much, but it completely throws my map out of sync, and now I need to resize an area in a beta. Shit.
--This seems like a neat idea, but we run into the problem of making it seem like either RED is defending the aliens or is the aliens, but...not alien-like?, and it just makes zero sense. Or it's koth and we're fighting over a point to destroy the aliens instead of destroying the aliens and maybe having conflicts on the battlefield?
In my map, I could have a stage where I'm in the alien mothership. [Aside, I see no logical way for two teams fighting one another to do this - the money reasoning of Frozen's is like a way for him to get out of having to explain other issues]. We would need assets for a spytech-like base, but with an alien theme (consoles, crates, barrels, door frames, etc.). Except, I don't know what I'll be provided with. How big are my alien-style doorways? I have zero clue, so I guess I'll map this alpha out with a 160-wide doorway. Sure, that sounds good. But my map is laid out in such a way that the wall there is only, like, 16 units wider than the door frame. Boy I hope the alien door frame model isn't much bigger! <Later> Oh hey the alien door frame model is out! YEAH! Oh wait, it's 196 units wide.
--...Yup.
Also, Ronin and BANG! make it sound like this contest is leading to something. My prediction: Valve and you are in contact and they want a new community map (I mean, let's be cereal here: they recently discussed how upset they were that they've been slacking on buying community maps) that leads to the new map that Valve is making related to a moonbase (I mean, let's be cereal here: you're not allowing a moonbase).
As Muffin (Umb) said, I don't like making something that leads to something I am unaware of. Just tell us what we're doing, and make the models BEFORE you announce the contest.
[And with that, I depart to a far away land where I am without a computer for 24 hours]
Edit: Also, what kind of aliens are these? Laser/energy-technologically advanced race? Virus-like race where they just infect our things and make the alien-y? A different kind? If I planned for an infection-like race of aliens to be holding the used-to-be-abandoned sawmill I want my team to secure to produce wood for our sword handles and demo shields, I'll build that way. PSYCH, they're just really technologically advanced! Now I have no way to alter my plans for this entire mid section. Gotta rebuild it halfway through the contest period!