Is it possible to set a subcategory to only apply to a specific subcategory? We recently had a mod developed in our speedrun to make drop RNG of two abilities that were a make or break it for the run 100%, and we're looking to add a Modless and Modded subcategory to only the PC leaderboards. However since the platforms were done as subcategories, I can't figure out how to make these subcategories only apply for the PC subcategory. Am I missing something?

That won't be possible unless your platforms for example would be sub variables instead of regular variables. But in your case, assuming you are talking about Lightning Returns, the platforms itself are regular variables. The best way you could probably resolve this is to make a new Misc. category for the mod and have it track no variables at all. As an actual category instead of a variable, the "modded" aspect wouldn't be applicable to other categories, but you could always try out how it works for one or two categories, instead of instantly throwing out an extra variable for every single category to track. Also looking at potential popularity for other categories, or even if it would be sensible to have for other categories. Either way, whatever you decide on, please consider not tracking the current board under a variable such as "modless" when you create another variable called modded. It sounds pretty off. Perhaps something like "Vanilla" or something along those lines would be more suited.