Well, summarizing everything I did with this adventurer, I initially went to the only Dark Fortress in the map and trained myself by slaying the goblin population. My skills went up to legendary axeman, armor user, fighter, wrestler, striker and kicker. However, since this fortress possessed near 10000 goblins and 23296 trolls, playing was a lagging nightmare. I was basically, hitting a key and waiting the game to react, while browsing the internet with my tablet.
Luckily, after training was over, I got out of there and started doing all the quests my lord suggested me at a reasonable travel speed (no lag anymore). Companions came and went. When I lost them, I quickly replaced them to avoid bogeymen and to use them to guide myself. When I didn't know how to get to specific location, I stopped fast travel, and asked my companions for directions to the specific lair, and they would tell me where to go.
The world in which I was had no vampires, nor necromancers so I didn't have to interact with those creatures at all. Instead I used my time to kill all the other night creatures I was told to. I had to swim to nearby islands to kill the beasts that were there, and I had to pursue every asterisk I found on the fast travel map, to get to those who were "on the run".
Finally I killed them all, so I decided to try the only vault in the map. Previously on my incursion to the dark fortress, I had found the demon leader, a Camel Monster twisted into humanoid form. My attempts to kill him were in vain (back then I hadn't boosted up my skills yet, so I was pretty much a newby demigod). Thanks to repetitive savescumming (yes, I savescum a lot
) I decided I was no rival for him and to kill him another day.
And so, as I was saying, once I slayed all the night creatures I was told to, I entered to the vault myself.
I achieved to kill everyone in there. However, I could not find the demon slab. I didn't want to make him my companion / servant, since I had nothing else to do in the map. I just wanted to banish him to hell again. So I said "Hey, all my offensive and defensive skills are legendary. I'll just kill him the old way."
So after that, I went back to the dark fortress, and it is now, that I'm in there, suffering the fortress lagging just to kill that demon, regretting my decision step by step. This is really slow.
So, after I finish this, I'm going to go to my old lord, claim the site and kill him. If I successfuly achieve this I'll retire my adventurer, and go back to Fortress mode in this very same world. Luckily, I'll go back to Adventure Mode when the lagging is pretty much fixed, but right now, I think I'm going to "retire" myself from it as well.
EDIT: I've discovered that killing the demon wasn't easy at all, even with legendary skills, so I'm going to back off and try the vault again. Also, when I returned to the Dark Fortress the building structure was different so I suppose the vault structure is going to be different as well. Or at least I really hope it is different. There lays my only hope.
In a semi-related issue I think I'm going to try to release the human prisoners in the fortress. That was one of the few missions I still have left, so...