Wow, thanks, I hadn't noticed that the secrets were listed there. Unfortunately it didn't solve the mystery. I'll keep searching for it. 

I haven't checked 1.70 code yet, but in the previous release, the lich fiend code was incomplete. Perhaps a planned boss that was scrapped, but still makes for a neat secret area macguffin. 

I did a somewhat long and derpy playthrough of this which you can watch here:

https://www.youtube.com/watch?v=wnRTYyQrkPA&list=PLzplQrZpMjlbiVqkKXID0JguzUTrv4V_J 

Finally managed to play this gem on MarkV

https://drive.google.com/open?id=1Tci8rxjAPg6TJhLKhxp_4zaOnVAk3YH9

https://drive.google.com/open?id=17sZOHJbqwNy981JOGMbiTpj1zJb9-anP

Thank you Sock and Giftmarcher, and thank you Baker for MV ) 

Does killing the 8 green spawns in Sepulcher do anything? 

Such an amazing map. It feels like the pinnacle of QSP-mapping somehow. An embarrassment of riches. Currently on my third play through. The first time I had only killed about half of the enemies at the end. The second time I really tried to find all nooks and crannies, but still missed a lot of secrets and secret areas. Now I'm playing it guided by quadro dcc's excellent (almost) All Secrets Playthrough, which is recommended for those hunting down secrets they might have missed. Anyway, loads of thanks for this unbelievable masterpiece!

https://youtu.be/obf2At8XkYw 

So I got all 50 secrets now, but I'm still missing one of the books. The guide in the readme says:

13. Water Cave, inside demon alcove. "Scampie Tales"

No idea where that is supposed to be? Of course, the readme is for this "stand alone" map release and I'm playing the version that comes with AD, so some stuff has been changed since then. Anyone who knows where "Scampie Tales" is. The annoying thing is that I think I've found it during earlier playthroghs. 

Found it! It was behind a breakable wall. So all secrets and books now. I must have spent more time playing this single map than I have on quite a few games. 

So I've put together a simple page with all secrets and all books etc. It's still ”beta” I'd guess as I'd like to change name on a couple of areas, some secrets are confusing visavi the readme, so I'd like to finalise the numbering - plus the screens are so small that they are pretty much useless.

https://sites.google.com/view/forgottensecrets/home 

For what it's worth, I've finished the Secrets > More guide. I decided to keep the area names just as in the readme to avoid confusion. The same with the numbering. where I've noted the discrepancies. I've also added hyperlinks to full sized images.

https://sites.google.com/view/forgottensecrets/home 

but nice work... time to break out this map again. 

Thanks! Yes, but I thought spoilers was a given in a secrets guide so no need to warn about it?

My obsession with FS has also made me revisit other maps by Sock and I really like the relative non-linearity and clever combat in them (Gendel's Blade and Nyarlathoteps Castle, for example). Brilliant maps. 

I was just being silly there. Go play "Horde of Zendar" for a treat! 

Haha, alright, I thought it was some kind of Func_Msgboard unwritten spoilers rule I had broken. 

The beta version is here, since it is not on quaddicted. Fully playable

https://www.dropbox.com/s/uht5cqfh906vjfl/ad_v1_50_fanP1.zip?dl=0 

What is this? Never heard of a fan patch for AD. 

That was before Sepulcher "official" was released and ad_chapters had an unused entrance to it.

So this is the "Beta" Sepulcher(named ad_e1m3) WITH a modified ad_chapters that makes the entrance usable.

However, this will of course mess up your current version of Arcane Dimensions if you overwrite the ad_chapters.bsp.

Jus' so you know ;) 

This new link only has ad_e1m3:

https://www.dropbox.com/s/jhhziy7td5v7azp/ad_e1m3.zip?dl=0

It should be on quaddicted, since the map is complete and it is very different from the final version.