I'm tying to identify an coin-op arcade game of the 80s
Coin-op limits the field, that's useful.
some kind of spy, who was chased by other spies across a building.
Chasing... and what else? Shooting? Dropping bombs?
There was at least an elevator, but it wasn't Mission Elevator.
I don't know of a game called Mission Elevator, but I've played my share of Elevator Action. Is this what you mean?
Rooms could be entered, that were shown from the top, with walls kind of like Berserk.
And this is where I lose it... an elevator but also top-down rooms? I don't think I've ever heard of that.
remember that unexplored areas were filled with a solid colour.
... and back to EA, where the areas were unlit for sections of the building and you could only see the doors and just make out the enemies.
And (less sure about that) items had to be collected
And EA had that too, in some of the rooms were briefcases you could pick up for bonus points.
To get this one, I think we will need some more details.
Can you be more specific about the "chase" bit? Was the entire game top-down, or just when you were in a room? Any other details you can recall about the graphics or gameplay?
You mention the graphics being simpler than Cloak and Dagger, but those strike me as rather basic indeed. You also mention it being a bit like Berzerk. Would you say the level of complexity of the graphics was very simple, just some lines and sprites? Is there another game you might compare it to in terms of complexity?