I didn't say alien invaders- only aliens!

Would be cool because then you wouldn't have to worry about enemys rocket dropping right on to your bunker, 20 dudes coming out and owning you, but they could still fly there from somewhere else so they could be repelled more easier way.

I like the idea of increased costs further away from your brain or from your designated space. That coupled with the already-there possibility of being shot down would balance things quite well, you COULD drop right on their base, but it's hard to pull off and expensive to attempt.

An additional concept could be little markers your men place around the map to extend your drop-range, making it cheaper to make further up drops. Part of the challenge would be putting them in places where they won't get shot, so it might be best to send out a clone with a digger and a beacon. That way they can dig a hole and put the beacon there.

(PS: Good call about the X-Wrap. I'd love to be able to make valley style maps. Hmm... I could try doing that with stone walls on either side....)