Paul Beakley, yes that’s it exactly. In fact, that’s the article where I learned about the fishtank technique.
There’s also the “Fish Tank as Intrigue” article, same author:
I like it better than a sandbox, because it’s more dynamic; I don’t have to wait for the PCs to dig for plastic dinosaurs. The NPCs are locked in a serious situation, and then the PCs arrive, and the NPCs all assume that the PCs are there to help them, or to oppose them! …and they react accordingly. The NPCs are “sticky”; once one has met the PCs, she can’t leave them alone.
Actually, it was good to read those articles again.