The Three Traditions
Working names throughout. Rename freely.
Everything in the galaxy runs on the same substrate. What divides it is what people think they are doing with it. Three answers, three cultures, and they have been arguing for thousands of years.
The Combine
Total industrialization, and no memory of what it is built on.
The Combine industrialized harder and earlier than anyone, and somewhere in the last several thousand years it stopped knowing that its machines are castings. Its engineers will tell you flatly that magic is superstition, and they are not lying: nothing in their training, their schooling, or their trade literature says otherwise. It is simply engineering, and it works.
They are the largest, richest, and most numerous of the three. Most ports are theirs, most shipping is theirs, and the standard sidearm in your hand is theirs. When someone says "the galaxy" and means a government, they mean this.
The Sidereal Houses
Both, deliberately, and at enormous expense.
The Houses industrialized without ever letting the hand-work die. They keep practitioners, apprenticeships, and traditions that the Combine abandoned as inefficient, alongside every bit of manufacturing the Combine has. A House vessel is engineered and also has someone aboard who can do it by hand when the engineering fails.
Fewer worlds, far older institutions, and per head the most capable people in the galaxy. They regard the Combine as sleepwalking and say so at every opportunity.
The Pilgrim Fleets
Magic only, and no industry at all.
Most inhabited worlds never industrialized. A handful of their faiths, over centuries, built ships anyway: vessels that cross the void because they are worked to, not because anything is burning. They are slow, few, beautiful, and go places engines cannot.
The orders that sail them hold that their ships are sustained by the divine. They pray, and the ships carry them, and in thousands of years nothing has ever contradicted that.
How they get along
Badly, and slowly, and mostly through trade disputes rather than war.
- The Combine thinks the Houses are decadent and the Fleets are a hazard to navigation.
- The Houses think the Combine has forgotten something it cannot afford to have forgotten.
- The Fleets want to be left alone, and largely are, because nobody else wants the routes they use.
Mixing them
The three are not tiers on a ladder and no world is purely one. A Combine port has House-trained specialists working quietly in the back. A hand-worked world will have one Combine-made generator that everybody depends on and nobody can repair.
Play the traditions as stances, not territories.