I definitely like the idea of a customizable space ship. Perhaps the base "levels" of a ship would be defined by its power plant. The power plant would then grant X numbers of units which can be spent on modules. And basic modules would unlock other modules. For example, you could buy an upgraded life-support module, which in turn would unlock a hydroponics bay, storage garage or a bestiary. You can choose to upgrade the life-support module further and build more or bigger or more exotic modules which make your ship into more of a base. However such specialization would be quite costly, and leave you with little defense or offense in space combat, and make your ship slow and consume huge amounts of fuel to get from A to B. Conversely, you could instead of buying that life-support module, buy a laser focusing array which would allow you to fire lasers to defend yourself. Or a shield generator to defend yourself. Or an upgraded engine which reduces fuel costs. The idea would be to allow players to specialize a ship, without allowing a person to create a monstrous ship capable of destroying anything with a sidewards glance, traveling between sectors on a fraction of coal dust, and carrying a planet's worth of chairs and tables. Upgrading the power plant would allow a player's ship to barely keep up even if min-maxing, but such specialization should come with heavy difficulty.
