It would be nice to have some AD&D style demons and devils

[sir_pudding]

DF7 has "Insane" as an alignment, which might correspond to "chaotic" but it doesn't have to be. In "Clerics of Order and Chaos" I discuss some options for different alignments for chaos deities in your game.

[demonsbane]

Originally Posted by martinl

For the purposes of many delvers, "Things" (team Squid) are barely discernible from "Demons" (team Evil).

And I believe there are good reasons for that. Here's something about it:

Originally Posted by Kromm

Finally, Elder Things aren't material. They aren't extradimensional in the usual sense, either. They are strictly speaking outside the concept of dimensions. I'm not partial to the D&D cosmology, but using that as our example: if the Ethereal Plane (meaning all the Ethereal Planes) surrounds the Prime and connects it to the Inner Planes, and the Astral Plane surrounds all that and connects it to the Outer Planes, then Elder Things lurk in whatever surrounds all that – what some D&D works call the Far Realm or simply Outside.

This extradimensional character, beyond the concept of dimensions, in a way (not bereft of issues) matches with the unmanifest, beyond any existence, which I mentioned here:

Originally Posted by demonsbane

Even deep layers of meaning redeeming "the demonic" by linking it with the unmanifest as the upper darkness, have nothing to do with the distinction you're looking for [it was among Demons and Devils].

Now, when they are just expressions of the lower darkness, which is also the cosmological bottom or what religions approximately call "hell" * (in an overall sense, without taking specific layers into account), tentacles aside I can't find any meaningful difference between Things and Demons.

Originally Posted by martinl

DF cosmology is kinds fuzzy.

What things truly are can be not immediately obvious for the adventurers, and IMHO it doesn't need to be.

* This is what the Hero System's sourcebook The Ultimate Mystic makes with Elder Things by interpreting them as Qlippoth.