"Pax" included design systems for both ships and the technologies that would be installed on them. The ship design was based around a fixed selection of "hulls" which differed primarily in mass, materials cost and the number of attachment points for technologies. The technology design system was quite complex, allowing the player to select tradeoffs on range/power of the weapons, speed/cost of the engines and so forth. Players could design the technologies, and then attach those technologies to one of the ship classes. Alternately they could leave the tech design to the computer, which would generate new technologies over time, and then manually select those technologies to design ships. In the extreme, all of this could be left to the computer, which would periodically generate new ship classes automatically.