Post hoc.
Or maybe in advance, if the GM tells the players what they have to do to earn XP (eg rescue the princess, kill the vampire or whatever).
The PCs don’t know how many XPs the diamond is worth until they appraise it. They don’t know how many XPs the dragon is worth til they kill or subdue it. There’s no difference.
And in the case of a story based adventure, as I’ve said repeatedly, no one playing Ravenloft doesn’t know that the goal is to kill the vampire. It’s self-evident.
This is not the same as a win condition established by the game, which then permits the players to make their own choices about how they wish to do that - choices about risk and reward, scouting out possible treasures in the dungeon, etc.
I disagree. There’s no difference. The players make their own choices in story-based adventures as well.
Yes, it is a thing that I've encountered. I've played plenty of railroading, GM-decides D&D. Thankfully not since the 2nd ed AD&D era. In my view it's bad RPGing.
Railroading is a separate, undiscussed topic.
And what does "exploring it", "interacting with NPCs", etc mean? These things don't exist. They are imaginary.
I mean…you had no problem using that word.
The way the players "act upon" a dungeon is by exploring it,
The game is imaginary. There is not really a dungeon. There is no Mr. Boddy. There is no Park Place and Boardwalk.
@AbdulAlhazred described a situation where a PC stuck their hand in a chest and it was sliced off. Where’s the mechanic for that? Where’s the reasonable risk/reward cue for the PCs there? How was that not “GM Decides?” How was that not completely arbitrary?Therefore, what we are really talking about is how the outcomes of declared actions are established. In the context of the dungeon, the fiction is artificially austere, generally quite simple, and - as @AbdulAlhazred has already posted - there are known conventions and tropes for adjudicating the relevant actions. The GM's key can also deal with most if not all of the salient things - distances, portals and furniture.
Once the fiction becomes about more realistic things, there are too many possible action declarations to be covered by known conventions, and the key can't even aspire to be complete. So the way those outcomes are established becomes simply by the GM deciding.
I mean, it's no coincidence that RPGs that aim to support more "realistic", non-dungeon-crawling scenarios, and that want to avoid GM-decides railroading, adopt pretty different action resolution frameworks from those found in AD&D. This has been evident since Greg Stafford designed Prince Valiant in the late 80s.
And yet, games exist that do this all the time. You just like games with an extremely fixed set of rules and actions (even though that doesn’t prevent silly results like the aforementioned hand chopping trap). As I’ve said several times, the differences in the editions produce different motivations from the players, but I think you’ve reached a set of conclusions about the game that don’t really hold water.
And I noticed you didn’t answer my last question.