The defenders demand
Controlled entry, disarmament, biological quarantine and supervised settlement.
They meanProve that you are safe before entering our system.
Heard asSurrender your independence and place your survival entirely under our control.
MOD.01
THE PREMISE
Centuries ago an advanced civilisation launched a one-way migration toward a nearby star. The destination looked empty: energy, metals, water, habitable ground. The fleet carried settlers, embryos, ecosystems, factories and the cultural memory of a people. It was never designed to return. The ships had enough reaction mass to accelerate, cross, brake and found a settlement — not enough to reverse course or wait between stars. For the migrants, arrival is the only possible future.
MOD.02
THE MIGRATION
- 01
Departure
A one-way expedition leaves its home system: settlers, factories and cultural memory aboard ships that were never meant to come back.
- 02
Discovery
Fast probes travelling ahead find the destination inhabited. In the centuries since the original survey, another species has exploded into orbit, the asteroids and the outer system.
- 03
Militarisation
The fleet cannot turn away. It will be most vulnerable while braking. Contingency planning hardens into doctrine across generations. Settlement mass becomes weapons.
MOD.03
THE DEFENDERS
- 01
Warning
Anomalies appear in the outer system: extrasolar probes, hidden relays, surveys of industry, encrypted traffic leaving the system. Some machines conceal or destroy themselves when approached.
- 02
Recognition
Fusion emissions and radiator signatures expose an enormous civilisation on a braking burn — armed, industrial, unable to divert.
- 03
The line
If the fleet enters and plants mines, reactors and foundries, it may become impossible to contain. The defenders fortify the heliopause: sensors, interception fleets, supply bases.
MOD.04
FIRST CONTACT
The species build a shared language from mathematics, astronomy and physics. They can name matter, distance, mortality and trajectories. Technical translation outruns cultural understanding. Sovereignty, quarantine, asylum and legitimate ownership have no shared meaning.
The migrants demand
Guaranteed resources, autonomous habitats and the right to keep defensive forces.
They meanGive us a future in which you cannot later exterminate us.
Heard asCede territory to an armed power that may eventually dominate us.
Both translations are accurate. Neither side understands why the other considers its demand reasonable.
MOD.05
WHY THE HELIOPAUSE?
FIG. 5.1 — THE HELIOPAUSE, CONTAINMENT LINE
The heliopause is not a political border. It is the final practical line of containment. Outside it, the migration stays dependent on finite supplies, ancient interstellar engines and a constrained braking trajectory. Inside it, the fleet can disperse among comets and minor planets, harvest water, metals and fusion fuel, and convert settlement machinery into a self-sustaining industry. The game is named for that line: the region where inbound trajectories meet the system's edge.
MOD.06
TWO SIDES, BOTH RATIONAL
It was never supposed to happen this way.
The incoming migration
They believe they are refugees facing an extermination blockade — a one-way voyage whose only reachable future is this system.
They cannot turn back. Reserves are finite; disarmament before independent industry would leave them wholly dependent on an unknown civilisation.
Break the heliopause line or the migration dies.
The system defenders
They believe they are resisting armed settlement imposed without consent — an industrial civilisation arriving on a braking trajectory.
They cannot allow mines, reactors and foundries to take root. Once the fleet becomes a self-sustaining industry, it may become impossible to contain.
Do not allow the migration to become an industry.
MOD.07
Two civilisations facing off at the edge of the solar system.
Fleet log
- 01
Departure
A one-way migration leaves its home system — settlers, factories and cultural memory aboard ships that were never meant to return.
- 02
Detection
Forward probes find the destination inhabited. Contingency planning hardens into defence doctrine across generations.
- 03
Militarisation
Settlement mass becomes weapons. The peaceful expedition transforms into an armed migration on a braking burn.
Defender log
- 01
Warning
Anomalies appear in the outer system: extrasolar probes, hidden relays, surveys of industry and encrypted traffic leaving the system.
- 02
Recognition
Fusion emissions and radiator signatures expose an enormous civilisation on approach — armed, industrial and unable to divert.
- 03
The line
Defenders fortify the heliopause: sensors, interception fleets and supply bases at the last practical containment boundary.
Contact
A shared technical language forms — matter, distance, mortality — but sovereignty, quarantine and safe entry have no shared meaning.
The Front
The first battles begin beyond the outer planets, where inbound trajectories meet the system's edge.
Neither side is morally simple. Every defensive measure appears offensive from the opposite direction. At the heliopause, each civilisation believes it has run out of alternatives. Each is right.