Thinking about CIU… its scope could be all but infinite.
Galaxies could be generated algorithmically, using coordinates relative to the initial galaxy as seeds for a random-number generator. Their overall characteristics – galaxy type and such – could be determined based on a number of general patterns. Within a galaxy, star systems could be generated, again based on patterns, using coordinates as seeds for random-number generators. Any time you go back to the same location, the same number seeds would generate the same things to be found there. Names, planetary and stellar characteristics, and missions could all be created in this way. The only limitations would be in terms of the game having to keep track of any changes that would need to be remembered from the default generated state. And in practical terms, such changes would have a limited lifetime. If you manage to clear all of the chickens out of a galaxy, and go on your merry way, if you come back a month later you would find that the chickens have returned.