Dear developers,
First, thanks a lot for the game! It gave me a lot of good time to remember.
After finishing the campaign a thought struck me. What PHALANX is fighting is a micro organism - the logical response would be a cure and a vaccine. And indeed such thing is already proposed:
http://ufoai.org/wiki/Proposals/Behind_the_Facade . But what if we go further - allow the cured aliens to join (after a lengthy recovery) PHALANX in a war of liberation?
That would be consistent with the story. Say, you are a cured Taman. And you learn that you, and your fellow Tamans have been used by some hive mind as cannon fodder. And now you are with the people who are fighting the exactly same fate and might be able to help your brethren. What's the logical thing to do?
That would enhance player experience. Adding aliens would add to the game depth by allowing for even more variety in tactics. Think of Shevaars for close-quarters fighting and a Taman spotter for night-time sniping. Think of an Ortok being not entirely happy to shoot at other Ortkos - forcing the player to choose between a morale drop and having to stun all the enemy (or own?) Ortoks.
That should be easy to implement. At least, no new artwork is needed.