Thanks to L. Curtis Boyle and Rob in the comments, I now have the “box” art and manual for the earlier (Spectral Associates) version of the game.

From Ye Olde Infocom Shoppe, which I found out also has items listed on Bonanza.
It looks like the manual is nearly identical, except for one important difference: it lists specifically what attack verbs are:
SHOOT, STAB, HACK, BASH
The idea, again, is that you READY the weapon in question (you cannot have inventory otherwise, so any items are dropped if you ready something) and then use the appropriate verb. It does seem like some weapons are more appropriate for particular creatures than others.
DAGGER, MATTOCK, DRAGON SWORD, PISTOL, MACE, SCIMITAR, MACHETTE, LANCE
My first real combat was unintentional. I had the game running in the background as I was checking the map and manual over and when I came back the wizard had arrived and done me in (this is at the very start of the game, so it appears the wizard can go everywhere except maybe the Sanctuary).

My second combat wasn’t a real one, because I ran across the dragon all I had was a dagger (which did nothing). I’ll show off the maps later; the dragon lair is quite early in rather than buried, but it can also be fairly easily avoided.

A quick extra comment on the text above: I was trying to see if ATTACK DRAGON had any effect (it doesn’t, but I didn’t have the list of four attacks from the earlier manual so I didn’t know that). I started typing the letters “AT” and was interrupted by the dragon. I’ve had cases where I’ve had a command interrupted where I just had to re-type it in, which means you’re in a literal typing match versus the computer.
Fortunately, at difficulty level 1, monsters really don’t hurt that much (unless you leave the game idling for an hour so the wizard can whomp you in the starting room). Here I am with a MACE using the BASH verb on a cyclops who barely gave me a scratch:

COND (condition) went from 255 to 239. The cyclops also left a treasure, the EYE OF THE CYCLOPS.
Later I bashed an orc which did a little more damage, but nothing to worry terribly about:

The main worry is while exploring, you sometimes meet an enemy before you are ready (given the inventory limit of the game is low just like Minotaur, I often didn’t have a weapon at hand), so need to make a prudent exit. However, it is possible to just zip by. I assume at difficulty level 3 this will all be much more of a hassle.

Notice my casual stroll by the wizard.
With the combat out of the way for now, let’s go over the map. I think I have nearly all of it, because multiple places tout the game as having “over 200” rooms and I’m at 197. This is not as large as Madness and the Minotaur; assuming I’m not missing something major, there’s only three floors, and each floor is eight by eight.
To make it easier to visualize, I’ve rendered it like an RPG map. It is no doubt incomplete (see the big gap on the top floor, for instance) and I don’t expect I’m 100% accurate (especially on one-way door locations, it was easy to walk through a corridor and miss the fact the way back was closed off).
Top floor:

S is the starting point, and the “ridges” are places you can jump over. The stair in the northwest corner also goes up to the Sanctuary where the treasures are stored.
Middle floor:

The arrows represent “landing points” for stairs which are one-way. The upper right 4×4 portion is a “maze” with a randomized stair, where the stair has a chance of sending the player back in the maze instead of going up.
Bottom floor:

The “dead end” leads to a Temple of Apollo where going south leads to a room on the second floor.
Just to illustrate the 3D-ness of the game, here’s a sample path from the start all the way to the northeast corner of the top floor (where there is an EMPTY CAVE):

The red side path leads to the dragon’s lair.
Along the way I had to jump a chasm…

…and solve a minor puzzle where a zither in a room could be played with a PLECTRUM (the use of this is given by a hint in both versions of the manual).

The route as shown otherwise relatively straightforward on the save file I was using, but I do again want to emphasize I’m at a lower difficulty and more things are supposed to potentially happen, and even at level 1 random traps can pop up. On one of my runs, a particular spot on the middle floor had a teleport trap which I was never able to disarm:

There are multiple places with boxes that suggest some kind of treasure, but I have yet to be able to open one. I might just not be holding the right key in the right place.

The spot I find most intriguing is at the SE corner of the top floor. To get there you need to jump over a chasm where it is possible to die if you are holding too much:

I don’t know what the limit is. This is being done at full health, so that isn’t an issue.
Here’s the actual room in the southeast corner:

The wood door leads “off the map” but could easily be a teleport, maybe to the empty section on level 1. However, I haven’t been able to get in the door; I assume another key is involved? Or possibly, there’s an arbitrary use of a magic item (which would be hard to test, given the chasm prevents carrying too much).
There are many other rooms which could potentially have something going on, but it’s not obvious what item I’m supposed to be using or magic I’m supposed to cast. There’s FAIRY DUST, for instance, and the verb SPRINKLE, but where should it go? Does it even get used at difficulty level 1? I also tried checking carefully every room underneath the gap in level 1 just in case there was something special, and this statue at a dead end looks suggestive…

…but given many of the rooms are just described for flavor, the statue may mean nothing at all.

This trumpet can be played, but I haven’t found anywhere where it has an effect.
To summarize, the various mysteries are
- The large gap on the map of the top floor and the single room missing on the bottom floor
- The reference to a “HIDDEN TEMPLE” mentioned on the OLD MAP
- The contents of any of the locked boxes and how to open them
- The wooden door past the deadly chasm
Plus, of course, any “ordinary” locations might randomly hold secrets.

Is there a way to read the carvings, maybe?
I think I’m ready to do a “fixed” run where I’ll save my game and notate where all the objects are (staying with difficulty 1 for now). I’ll likely need to abuse the unicorn RNG just like Madness and the Minotaur (assuming that trick still even works!) Also (again like Minotaur) I’ll need to take many trips to get objects to the right places as the inventory limit is tight. Unlike that game you don’t have to deal with a constant state of decay, no matter which difficulty level you play at. Your condition only goes down upon being hit by monsters; on difficulty 3 the monsters start to hit faster.
I feel like this whole adventure roguelike thing would be a lot funner if instead of the roguelike aspect being combat and item placement, it was more related to puzzles. Sort of like what some of the Humongous Entertainment games did where you would get different puzzles on different playthroughs, but with the factor that maybe the puzzles won’t be necessary.
This one must date back to at least the first half of 1982, as there’s a run of adverts in 80 Microcomputing starting in May 1982.