.....
I would argue that the very best D&D games occur where:
#1. There is a well-detailed, well-thought-out setting that can be used to tell numerous stories (i.e., tomb raiders, complex politics, what-have-you).
#2. This setting includes numerous thematic "pay off" points, where these points can be any number of things, including foiling villians, finding a big haul, discovering secrets, etc.
#3. The players make characters that make sense within the context of the setting.
#4. The players are encouraged to make choices in the setting. This means that, on any given day, there are a number of adventure locations and/or threads that the PCs can follow up on. It also means, within the context of the setting, that they can choose threads that the DM didn't necessarily realize were threads ahead of time.
#5. Their choices have real consequences in the setting. This can, and should, go so far as to change the nature of the setting if the PC actions are momentous enough. It should also include real consequences for the things they decide to ignore -- the world should move even when the PCs aren't pushing it.
This means that both the "illusion of freedom" mentioned upthread and the "PCs determine all" are both extremes that
detract from rather than
add to a fun game.
At least, IMHO.
RC