The game is looking great, an Ultima like game world awesome!
Now I don't know if any of these ideas are still possible for Lurking II if you can add that it's great otherwise if you can add it for void or the other 3D games that would be really cool to.
And you mentioned you were not sure about putting it up on Steam there's a steam RPG that has worst graphics and has like a million downloads called undertale for some reason I got a real Buzz about it and got popular so you never know here's the link
https://store.steampowered.com/app/391540/Undertale/
I would ask you to please not forget about good Quest writing I hope you guys have played something like Fallout or Arcanum which has really interesting quests and is giving you different options on solving them. I think that makes for a much much better game so if there's a quest to get to a place you would have more than one way of doing that, you might be able to use stealth, might be able to use a conversation option, find a secret entrance, or disguise or even then combat.
One example of a quest could be so you have to get in to a walled town it's not letting anybody in so you have these options.
1. Stealth you can try to sneak in have a have the Rogue climb the wall and then either lower rope for the rest of the party, this would only require a skill check for the rogue character and then skill bonuses for the rest of the party.
2. Exploration if the search for an alternate secret tunnel that goes into the town
3. Disguises the party has to find some disguises as merchants and they get on to a merchant wagon and enter the town like that or something similar
4. Dialogue character that has to use bluff or something else to convince the guards to let them in as they are percentages of high importance or even Nobles. This could be made more of a challenge if there are several conversation options to choose from in you have to carefully choose the best ones.
I believe strong and interesting quests instead of just fetch Quests are one of the things a lot of game developers these days kind of skip over and it's one of the most important things for great games that people look at.
To get a wide sense of enjoyment from many people I think you should definitely focus on that, again take a look at Fallout and Arcanum for some inspiration if you can or if you have already.
Also I hope you're taking into account cover for combat specially for ranged, so it's not just a click fest you would have to use the environment and buildings to your advantage.
These kinds of little features would really add a lot of variety to the game play so you're playing for 50 hours the parts won’t feel like they're dragging or getting tedious that way.