The designation of acts is purely an arbitrary one, and something that most RPG development teams I'm aware of (and I know people in several, and used to belong to one) do. Hell, even DD had three acts: the Diabloesque opening city, the extremely large and non-linear world, and the (sadly) empty desert. It's just a convention. It's what you do within any act, and how you join 'em together, I think, that gives that sense of non-linearity.
Good points. However, DD had at most 2 acts. The opening dungeon did not have to be done right away. It certainly made it easier to do it first, but you didn't have to. The desert was so small compared to the rest of the game I thought of it more as an encore than an act. <img src="/ubbthreads/images/graemlins/delight.gif" alt="" />
"Wizard's First Rule: People are stupid" - Zeddicus Zu'l Zorander
