broad strokes of the setting, picked at the major elements, and showed some of the little cameos and campaign options available to players and GMs.
So to wrap things up, I decided to list some campaign premises (a.k.a. the more popular term now, campaign frameworks) that can be run in the setting.
The three major default campaigns come from the major powers / political factions of the galaxy.
The most straightforward of the three is the Pan-Solar Empire. This is essentially a no-Jedi Rebel Alliance campaign just waiting to be run. The fact that it isn't Star Wars means that you don't have to deal with fans waving books of Star Wars canon in your face every time you bring out a different kind of stormtrooper that wasn't in the movies or books. Plus, you get to do a lot of "wahoo" type adventuring on seedy planets on the fringes of Imperial power, and some tense infiltration work against well-funded, jackbooted military types on fully armed and operations battlestations -- because the RPG does have vehicle and space combat rules taken from Fuzion.
Almost as straightforward is the Interstellar Federation. While it is essentially Star Trek, there is some variance in terms of power levels here. You can ratchet them up to Next Generation levels, or bring them down to Original Series levels, but the implication is that the might and technology of the Empire should be capable of giving them a run for their money.
However, with the existence of the various arms of the AstroPol, a Federation-empowered law enforcement organizations, you can also run planet-, system-, or Federation-wide campaigns that deal with crimes committed against Federation citizenry. As AstroPol Agents you can hunt down high-level criminals in the riches systems in the Galaxy, while as AstroPol Rangers you can keep the peace on the frontier.
Now it's not explicitly stated, but based on the original source material both these settings are fairly optimistic -- there's a prevailing belief that despite difficulties (and insurmountable obstacles) good will eventually triumph over evil.
That's not necessarily true in the Old Earth Empire, which has a dystopian feel tinged with cyberpunk ethos. Blade Runner could have happened here, alongside Alien and Aliens, and Predator. Campaigns with cynical heroes struggling to survive in systems dominated by mega-corporations.
Those aren't the only possible campaigns, of course. You can have mixes between the mini-settings -- with Interstellar Federation spies going deep into the Pan-Solar Empire to aid the Rebellion with new technology -- cutting edge mecha. You can have Old Earth Empire mercenaries squaring off against criminals with slightly more superior technology from the Interstellar Federation. You can even have a Pan-Solar Empire battlegroup fall through a wormhole into the mysterious Centaurus Quadrant and have to battle their way past strange aliens and mysterious megastructures back to their home sector to suspicious superiors.
Lightspeed has a good mix of SF-inspired settings kluged together without necessarily losing the cores of each, allowing riffs and homages in a holistic setting. You may occasionally wonder how the entire socio-economic-political structure holds together, but there's enough space -- lacuna -- for the GM to come up with whatever rationale he can and the just run his campaign in whatever sandbox he's built for himself in the overall setting.
Here's hoping that Lightspeed eventually finds new life with another system that's more well-supported than Fuzion.