In-game money is in the form of raw metal, which is mined on the planets. The same metal is used to build the planet and ship parts, so the money available is a fixed amount of that mined which is controlled by the tax rate. Setting the rate higher takes a larger percentage of the metal to be set aside as money, but requires more people to collect it and thus reduces the rate of construction. Some planets have very high amounts of metal but are otherwise poor quality; these "metal planets" would be colonized, mined as quickly as possible, and then abandoned in favor of planets with higher growth potential. Additional money was generated by setting limits on the number of parts that would be stockpiled at the docks, with the excess being exported.
