What if you could make your bases have a different look or style to them? On the concept art for the Covenant base it had a bunch of different things that they didn't go with. I'm sure they could make some of them unlockable with achievements. They could probably do something like this for the UNSC too.
When life gives me lemons,
I make beef stew.
Gt: Mr Sticky100
New FF: The Final War
I would appreciate comments/critisism