Hi everyone i had two idea that could be pretty cool for this type of game.
If you either played doom 3 or used GTK Radiant to make Doom 3 map(s), then you may remember that Doom3/Quake 4 had very nice Interactive GUI for exemple in doom 3.
The nice KeyPad (when you where hovering the texture (textured on the geometry face), this was displaying the chrossair on the texture itself (small cursor) so you could click on the button (from the texture) and input the password of the keypad that was a pretty good feature in-game and there was alot of interaction on texture.
(GUI - Interaction Texture) can be used to trigger action of self-object such as door or un-linked object, just a nice way to trigger something.
Second Idea is the hollographic building, took the idea of "Red Alert Online", this was pretty cool to make a huge "fake base" by building false structures which granted the advantage to "spoof a secondary base" while it's only fake building and not really the real base lol.
In murnatan this could be tricky on huge map to do this kind of thing, for a gameplay reason the building would look's like Holographic ( textured / transparent) from the Human-Side (texture need to be blur/blue to look's holographic, or you can do it in green as well) from the Alien Side this would look's like real building !
Alien Sensor detect all closed range building, what about messing around with their sensor and making mass fake building to annoy their sensor