Personally, I'd say that if there are calculations within the program of X Y and Z, then the game is 3D. I believe in Dungeon Master, when you'd throw something, it had a specific distance that it would travel before it fell to the ground, and I think if it hit a creature at a particular distance, it'd do more or less damage.
So I'd say it qualifies as a 3D game, in both play and visualization. You could even go up and down levels.
I do always find it funny that Wolfenstein 3D is always brought up as being the first 3D game. Alternate Reality had fully textured walls many years before Wolf3D did, and apparently in the original design, he was planning on doing full 360 degree movement. He just thought that the players at the time would be really confused, and the maps would be more difficult to make. Amazing that the creators had managed to do the things they did on the 8-bit machines. It's a sad thing that AR: The Dungeon was never released for the Amiga or any 16/32bit machine for that matter.
slaapliedje