Can't find any option to add another game as a Category Extension (in main game setings). Do I also need to be a mod for CE game?

Now we have 3 runs of this thing, so I think that should motivate to add it to CE.

Honestly, pretty fun category, having all upgrades at the start won't make the grinding feel awful and it is just like NG+ runs of today games, where you can choose easiest difficulty. I see no reasons of this not being a thing on the boards

I am a verifier on the game, and for some reason I can see only one page of verified and rejected runs on Mod Hub, what seems to be an issue?