I’ve thought about writing a game in the Kerkerkruip universe, but I don’t know enough about the universe to do it. Probably could learn though, considering the wiki is a thing.
You’re very welcome to write a game in the Kerkerkruip universe! I think I can give you some useful pointers.
The essential thing is this: Kerkerkruip, in both its overall aesthetic and its approach to world building, harkens back to the sword & sorcery tradition of Robert E. Howard, Clark Ashton Smith, Fritz Leiber, and so on; not to the high fantasy tradition created by Tolkien. Tolkien’s genius lay in the detailed creation of an entire world with a vast history. Before he wrote a single word of The Lord of the Rings, Tolkien knew exactly what the world was like and what had happened in the millennia preceding his story. This approach has been widely copied, if perhaps never with the same level of success, by writers (e.g., Robert Jordan), pen & paper designers (e.g., Forgotten Realms), cRPG designers (e.g., World of Warcraft) and even movie directors (Star Wars). It is because of this that people talk of “lore” and of what is and is not “canon”.
But that it is not how fantasy writers before Tolkien and to some extent after him approached world building. They weren’t interested in having a fully worked-out world. They were interested in telling gripping tales of adventure, and they thought up new parts of the world as they became useful and necessary for the stories they were telling. I’m pretty sure Howard had no idea who the 15th king of Aquilonia was, because I’m pretty sure he didn’t care. He cared about the fact that it was a country with a certain mood and culture, and that Conan had killed its previous king and was now rather tentatively accepted as its new ruler. That’s the seed of adventure. So these writers were rather relaxed about their worlds. They didn’t care about “lore” and “canon”, or even strict consistency, and often had no problem with other people writing stories in the same universe and thinking up new things.
So that’s good news! Here’s the right approach to writing something in the Kerkerkruip universe: pick some details you like and do with them whatever you please. The monster and item descriptions often hint at people, events and cultures. But none of them have been worked out in any detail, so you can just grab something you enjoy and either build a game around it or mention it in your game. And it there turn out to be minor inconsistencies between your game and Kerkerkruip… well, we can be relaxed about that.
The most important thing is maybe to get the tone right. The world of Kerkerkruip is violent, decadent, colourful and it does not contain any of the overworked clichés of contemporary high fantasy (no goblins, orcs, and so on… unless they have a twist and are quite different from what we have come to expect).
Anyway, I would enjoy seeing more Kerkerkruip games very much. 