This is a very cool concept, vibe is immaculate, and in the end I did enjoy my time with it.
But I've gotta say, the UI is what really limits you. It could be so much better if I didn't spend first few runs just figuring out what is what. I did for first few runs thought the little star in the middle is the faith and it totally confused me. Tutorial would solve it, but who wants a tutorial? have a little window that displays on hover next to the stats that will say "your current fuel" and "fuel cost for the next voyage" or something like that. Just let me know in other ways what actually happens any time I pick a passenger. A little animation next to the stats informing that you lost -1 faith when you picked this guy. Especially if we don't know one of the effects. Or when hovering on the Upgrade ship or buy fuel button - just a little pop up that informs me what will happen. I know the upgrade is a little mysterious and you don't know what will happen - but then just say this! have a little window that displays on hover and says that it "consumes random amount of faith for a random upgrade".
I think a lot of people would just stop playing because they don't understand what's going on, and that's just sad because there's much to enjoy here! :D