Alright, I know a lot of people dream about DF because it's a very imagination-based game and you do a lot of planning about it. But this was ... weird.
The game was obviously a game still, but in actual 3D, with the concept of blocks conserved. So it wasn't HL2, it was DF, just in a 3D model. The dwarves, for example, were 3D dwarf faces
Second, it was multiplayer. I never got to see the other player's dwarves, though.
Third, I didn't build part of the play area - it was an underground space that I assumed was a mirror of the other player's premade space.
So the game revolved around military dwarves and civilian dwarves. There was a standard type of gameplay going on, but I would occasionally offer a dwarf to be evaluated by ... something. This something would decide if the dwarf should be military or civilian. After the decision, the offered dwarf went off to the play area that was static and that I didn't build. I could then no longer control him, just watch what was going on over there.
Over in the computer-controlled section, our dwarves were still separate. But the civilian dwarves were running around gathering supplies and stuff, like they normally do. And the military dwarves were jumping on a huge drum. If the drum beat enough, it would summon Armok and destroy the other player's dwarves.
I was restless all night, kept waking up, and kept coming back to the dream. Armok never showed up. I guess that's what I get for picking up a dream at v1.0 huh?