it runs on steam

Well I guess it “runs on steam” is a bad theme but good for me - I can work in any thing it into any sci-fi type game setting. I would just the ships collect steam that is floating around in space near stars and use it as a basic building block. The H2O is needed to fuel the ships in some way probably for the still semi-organic brain they use … so every thing will really run on steam as the main fuel source.