I've played through this game a couple of times and am very interested in speedrunning it in a new category, hopefully something more towards a 'good' ending or even 100% completion. What would be an acceptable added category?

I'm happy to add new categories if they haved a clear ruleset and at least one video of a completed run. If you want, you can join the linked Discord server, we have been discussing about new categories there

Hardcore Rave Kim% would be fire