I would like to see categories that are a little less about the imaginary branch of science in which an advance was discovered and more about the practical application of the tech.
I disagree, which is why my made-up non-functional multiple-choice tree
goes in exactly the opposite direction.
I feel like it's better for there to be a bit more variety within a category, so that it's not just a matter of "OK, I researched a detector, now I have to choose between researching another detector, or researching something else." Instead, it's better if the player makes a tech decision, then once the tech is researched, he gets to make a choice between a very different set of options, because the new techs that are available to him are very different from the ones he just researched.
You are conflating two different issues. My complaint here is about the categories
. There's no rule that a tech can only unlock new techs in the same
category. But i would argue rather strongly that for instance, planetary stealth screens should not be in the "ships" category merely because the technobabble explains them with similar imaginary science , and some ship part tech is a prerequisite for the planetary stealth screens. Weather planetary stealth screens should have ship part tech as a prerequisite is more debatable.
I also disagree with your assumption the only interesting research decision is between the new techs unlocked by the last thing he researched. Weather detectors are all in the same branch or scattered willy-nilly all over the tree, the player is still making the same essential choice-- weather he wants to prioritize better detectors now, or something else.
Of course there is no category that that planetary stealth screens, or a good amount of other stuff could naturally fall in. That's what i'm compiling about. Because i'm worn out i don't have constructive alternatives at this time.