So I love world-building, and put clinically insane amounts of work into it. That is, from my perspective, great.
But, I do not harbor the illusion that the average reader actually cares about where all the deserts are. They don't. They're there for the plot and the characters, and pages spent lovingly describing the world will be met with a sudden loss of interest on their part. This is not their problem to fix, as it would be pretty daft of me to expect people to not read stories for the stories.
What this really means, then, is that only the bits of the world that are relevant need to show up. The rest is all still there, of course, much as the currents of the North Atlantic are still there in a Sherlock Holmes novel, but it never needs to be mentioned. This runs quite counter to the inclinations of some writers I've run into, who appear to believe that any detail is good detail, and thus pack whatever they write with infodumps on whatever they think might be involved in some way, even - or maybe especially - if it has no relevance to the plot.
If the way your starship's engine works never enters into the plot (or, if you're making an RPG, the gameplay of the RPG), the readers don't need to hear about it. You can have it all figured out in case someone asks, sure, but don't stress out about it if you don't understand all of the tiny nuances, and don't regurgitate every detail in a vain (of the self-image variety, not so much the futility sort) attempt to show the hours of work you put into what the reader is holding in their hands. Quite apart from making you look whiny, showing your work for the sake of showing your work is a recursive, stupid activity that tends to ruin your work.