Four planets. Between them, only ships somebody built
Every planet has its own day length, its own resources and its own
role: the system is built so that not one planet is self-sufficient. There are
no portals. The only way off a planet is a ship the players assembled: hull, engine,
fuel, life support. That is weeks of work and a dozen specialists, so the first ships
will be jointly owned out of sheer necessity. The class II engine is not in the
Library — somebody will have to invent it first, and at a loss.
There is no telling in advance how long a flight takes: the planets follow their own orbits,
and the road between two of them runs from a few hours to several days, depending
on where they stand right now.