We (primarily JWinters007 and myself) just completed Nullius after almost 400 hours of casual play (technically we still have a few biters left to seed).
The whole factory has just over 200 trains (almost entirely 1-4 trains), and 250 stations. Our main base is fed by around 45 stations supplying raw materials, a random assortment of intermediate items like rubber or Aluminium wire, and bioscience packs.
It is powered by an array of around 10,000 solar panels.
Nullius does a brilliant job of keeping the basic play of Factorio, but adding lots of new and different challenges. Managing the disposal of unwanted byproducts was often the most challenging part of a design.
The mod is very well balanced, with the right techs coming along when you need them to enable further expansion, and without having to really grind for any techs (except the optional ones at the very end which we haven't unlocked). The end game challenges are sufficiently tricky without being annoyingly tedious.
All in all Nullius was fantastic fun, a great addition to Factorio. If Wube had come out with the next version of Factorio based on this I would not have been disappointed.
