I would like to give just a hint. Missed creatures to interact. It would be nice if it had animals and other creatures to kill or interact during the exploration of the planets.
I like the idea but i think it would crowd the game a little. Now if the Fallen and Hive had wolf or tiger like creatures that would attack you that would be interesting and it would make the game seem a little more natural. Think about it the military/ police use animals as weapons all the time, why wouldn't aliens use them.