Right now there is no ground, All I'm going to do for the above ground is throw a box up there....Model the ground, then add tunnels and other ways to get underground....But I guess I'll add a little plane up there to give you an idea.
Added:
The green Highlighted thing is a Scorpion;
Added Again:
Don't mind the polycount, thats just the Tank. The level itself is 678 Faces