Instead of having just factions? have a clan based one, where clans fighting against each other (in games in general) take points from each other. of course clans get power points by taking a planet that has been taken from another clan or colonized.
I believe we could use "exp" as a currency known as metal (or some other cool name) . players get exp from game which is turned into currency, this currency can be used to establish a space port (to colonize/build a fleet) to take a planet to suddenly get points.
In games, where there are other clans present, clans can put a wager of power points and whoever wins takes the power points.
these points can be spent to "upgrade" a planet/space port to get more points from the planet over time (and establish defenses)
This is a basic idea. but could be further expanded to include stuff like planetary resources.