What's the Name of That Book??? discussion

I read the book in the early 2000's maybe late 1990's. Definitely before 2007 when I moved away from my library. The book was in Danish and I don't know if that was the original language.
I have no recollection of looks, but it wasn't a big or heavy book. It wasn't for children, but it wasn't a heavy or serious read. I'd have been a teen/pre-teen when I read it.

It was about a computer programmer working on a game at a company. He was an adult (late 20's, early to mid 30's) and seemed to have a slightly antagonistic relationship with his co-workers (boss was a hard-ass/incompetent, female college had nice knockers but was a bitch, that kinda attitude).
Most of the story takes place inside the game, which I can't remember how he enters. I think it was a planned part of the programming process? Maybe even how they make the game (worldbuilding?)

Anyway, I remember him standing on the thatched roof of a house in a medieval village trying to get a handle on his programming/creator/magic powers, while in some sort of fight with his co-workers who turns out to be evil.
At some point he tries to recreate a computer and ends up with Mimir's well of wisdom because the world is medieval and incompatible with tech. The well functions such that you have to drink a cup of water for each question and the answer will appear written in the water. The MC drinks and ask questions until he needs to pee and when he's done, the well doesn't work for him anymore.
He also (in his sleep I think) creates a female vampire with bat wings and fine white fur. She might be a character he has played roleplaying games with. Or that might be another lady? At some point there is a vampire count who want his help to get a wife as he is immortal and alone and.. that might be when the white vampire lady shows up.
There was no explicit content but it was heavily implied that he had more than one of the ladies and maybe at the same time?

Spoiler (maybe?)
In the end he somehow meets the consciousness of the server (maybe?) in a big abys and they communicate by creating small 3d pictures they manipulate to tell a story and I think he shares his consciousness/knowledge via brain meld? And this somehow leads to victory in a conflict I can't really remember.

It is not The Wiz Biz or Off to Be the Wizard.