"Forces" use the game's individual unit strength estimates, which can be found in tables in my FAQ. I omitted starcruisers, Vanguards and nebular ships from my calculations since they're all pretty much inconsequential to the current state of the galaxy.
The galaxy has three "age cohorts" right now. These represent powers that entered the game at about the smae time, and are not neccessairly allied to or associated with one another in any respect except general size and maturity.
The oldest cohort are a little short of a year old and constitutes the survivors of the Barricades Pact: RoR, Felor, and Finnian. This once-dominant alliance won a spectacular series of wars to become the galactic hegemony but now may be defunct. It's not clear whether their mutual self-defense pact is still in effect. Of these three, the RoR is by far the healthiest, with Finnian hanging on in enclaves across the galaxy and Felor in a sad state of decay. RoR is most robust and dominant galactic power in an absolute sense, especially since individual RoR planets are generally protected by the RoR's enormous Gorgos fleet. RoR has a presence in nebulas, but few nebular starships.
The second 'cohort' is just a single empire, Terran. Eldritch jumpfleets have been decisive in previous galactic wars and in this respect RoR is challenged by the insurgent Terran empire, which is only about two months old but has grown to rival it in size and organization if not in absolute power. Terran's Eldritch fleet is the same size as RoR's, but the rest of the empire is less mature, with fewer starfrigates (starfrigates are critical defensive units and can also be used offensively, albeit extremely slowly). The two major powers' capitals are less than 500 LY away from one another, separated by a thin nebular band. Terran and RoR use the same star-cluster topography, with Terran generally avoiding nebulas for the most part. Terran has individual unconnected sector capitals distributed across much of the rest of the galaxy, suggesting plans for future growth or warfare.
A third cohort entered the game about a month ago. Union of Worlds, BOYCOTT CHRONIMIUM, Reformed Empire, Chaos Undivided, and the Klingon Empire all pursue their own mysterious agendas in the galactic south.
- Reformed inherited a big jumpfleet from an abdicated empire but has not grown much since its initial expansion.
- The Klingons won a costly war against a pirate empire and now field the 4th-strongest jumpfleet in the game, but have not consolidated their empire since then.
- BOYCOTT doesn't build any chronimium units. It does have a lot of Defiances, which are pretty much the only low-tech unit that can go toe-to-toe with Eldritches.
- Union of Worlds has a tidy empire to the east of Finnian's capital but may face challenges to further expansion if it stays in the Trade and Enterprise doctrine.
- Chaos Undivided has been pretty inactive for the past few weeks and doesn't seem to have quite gotten the knack of how to build ships in quantity.
There are a few other small empires but it's not clear whether they're still active or not.