The DM can't put them there as potential adventures; the players can't put them there as potential adventures (true if the DM is <rightfully> given purview over the content of the game world), and my problem is I can't think of anyone else who can.
The GM can put them there
in response to a signal sent by the players. As in my example of the player whose PC's goal is to seek vengeance upon the lizardfolk for destroying his family's farm; and who finds - via the fiction that the GM narrates (eg word from the militia HQ and mercenaries' guild) - that the PC must choose between
defending the farms against the orcs or
leading a raid on the lizardmen with the other defenders of the tower.
what if any mechanic did you use to determine if, when, how, and by what the party was interrupted or threatened during their 18-month quasi-rest in a ruined tower?
I mean come on, it's a ruined tower - if nothing else there had to be at least one or two adventuring parties wander through during that time, looking for the loots and some heads to bust!
Lanefan
In your world, [MENTION=42582]pemerton[/MENTION], are there no other adventuring parties out there? I don't mean ones that actually get played, I mean off-screen ones that might take on an adventure the played party ignores with consequences of such adventuring (if relevant) made apparent later to the PCs; and-or ones that might literally or figuratively compete with the PCs for the same resources e.g. two parties are after the same McGuffin at the same time. (in your example, what if the dark naga had several charmed operatives all out seeking blood, each unknown to the others, with all the reward going to whoever got back with some first?)
I think I posted about this upthread. The mechanic that determines this is narration of consequences for failure; and also potentially as an element of framing.
For instance, when the players failed an orienteering check to navigate out of the Bright Desert to the ruined tower (which is in the Abor-Alz), I narrated, as a consequence of their failure, that when they arrived at the first pool at the hill's edge (where a stream collects in the rocks, before running down into the desert sands) they found it had been fouled. Investigation revealed it had been fouled by an elf. This directly addressed the Belief of the elf PC (who was leading the party out of the desert) that he would
Always keep the Elven ways.
The PCs chased this spiteful elf, and there were various other events involving him, mostly as an element of
framing (eg when the PCs arrived at the tower, someone had recently filled the well with rubble - the elf, of course!; and after the PCs failed to find the mace in the ruined tower, the player of the mage PC said "Of course, the mace is going to be in the hands of that elf" - which it was).
It's deliberate on the part of the GM, to maintain the pressure on the players (via their PCs) and hence force them to make hard choices in order to try have their PCs achieve their goals.
If this is in fact how BW is supposed to be run it's small wonder I won't go near it: it bakes in the attitude that the PCs are special snowflakes and that everything in the game world revolves around them and them alone.
The PCs in any world are but a very few of a much larger dynamic population, some of whom are and always will be bigger fish than the PCs are
I wouldn't agree with this - I would say that, again, it involves a category error. The game bakes in the attitude that the
players are important - they are here, with the GM, to play a game - and
the shared fiction that is the focus of that gaming revolves around the doings of their PCs.
That does not preclude their being "bigger fish" - examples that have already come up in this thread include the balrog-possessed brother, the dark naga, the tower-owning leader of the sorcerous cabal, the Gynarch of Hardby, and (I think he's been mentioned) the abbot Bernard the Holy who is in Hardby to officiate at the Gynarch's wedding to the cabal leader. There are other "bigger fish", too, whom I haven't mentioned yet (eg the Evlish sea captain Eltan, who tried to return the Princess to her mother the Queen of Celene after rescuing her and her friends in the Woolly Bay; and Wassal, the leader of the Bright Desert tribesman who took some of the PCs captive before sending them out into the desert so as to be rid of their curse).
But those bigger fish figure in the events of the campaign as part of a context centred on the doings and the aspirations of the PCs; much like in most other forms of serial fiction.