Alliance are a serie of different mods. On the Star Wars GC, you can play the civil war Empire vs Rebel era + Black Sun and soon the Republic and CIS.
Another addition, walls with weapons. There will be a different design for the Rebels, Empire and Black Sun. This designs will be shared with other factions.
Before you think about it, it will be light weapons, they will have not the power from a normal turbolaser turret and they can not damage some special units as a AT-AT.