So, the find the clues kind of mission could only work if the clues spawned in random loot rooms in the world, and the mission wasn't entered until the players found them. But the clues couldn't be spawned in other missions.
Well, that's not entirely true. The problem is that the clues would have to be some sort of generic clues -- in other words, if you find "Clue #1" through Clue #6, you could find those anywhere in the world (outside of missions or in missions) and then bring them to any "Find the Clue" mission to solve it. And I guess it would then take away all your clues, making you start over again for the next find the clue mission.
The problem is, I don't think that would be too much incentive to do these missions, speaking as a player, because it relies on: a) being able to get all those clues, and then b) being able to actually find a find the clue mission to "spend" them on. The other possible outcome is that I don't know what a find the clue mission is, and I enter it, and I am unable to proceed in any reasonable amount of time because I don't have the clues, and thus I'm incentivized to just brute force it.
I'm okay with some missions having impossible conditions if you enter them unprepared (no gills, so you drown if you are silly enough to jump in the water -- you learn fast not to do that again!). But having it be possible but nonoptimal will just lead many players to brute force the solution, leading them to annoyance and complaining at me.
I think that clues are more interesting if they are unique rather than generic, as well, meaning that sort of thing really would fit better completely outside of the mission structure. That sort of general mechanic just doesn't "feel right" to me with missions. Not all the gameplay is intended to be shoved into missions, remember -- more of the persistent exploration and "I found this thing, maybe I can come back later and solve it" sort of mechanics really would be aimed at the world itself. Not prior to 1.0, but it is something I'd like to do.
Could the (admittedly poorly named) steal the loot mission work? It would generate different mobs based on whether or not different missions were still active. Nothing inside the mission would change after being generated.
That sort of thing would be possible, yes, but I should explain a bit more the mechanics that we have. Basically, these would work like Ice Pirate Patrols, I think. Those are what we call Macrogame Environmental Threats. They are some sort of thing visible on the world map, and they threaten regions within a certain radius of themselves. They aren't missions directly, but missions could pop up from time to time to let you eliminate them. Also, guardian powers could be used to eliminate them. And they might affect other missions to make them harder.
So, for instance, perhaps a better way to make this particular idea work in the current structure would be to have a ring of elemental-resistant monster "armies" that get placed in a ring around the overlord, or a lieutenant. You can go into the overlord's keep without dealing with these, but you'll be seeing TONS more monsters with all these extra immunities. Man will that be hard! Instead it's a better idea to either do missions or use guardian powers to clear out those elemental armies, and then you just get back down to the base overlord difficulty.
In terms of having other macro-game locations like a rare commodity cache, or the site of some elite loot, that's something we'd want to do, but not prior to 1.0. That affects too many things that we'd then have to balance. So having a single Steal the Loot mission that's in the center of these armies wouldn't really work, because missions will start expiring soon and then it might move. THAT said, any missions that did happen to spawn within range of one or more elemental armies would automatically get the extra enemies spawning in them, so that would actually work really well in terms of making nearby missions hard, and thus "linking" them in a very decoupled way. If you're a programmer, kind of the difference between a DLL and a statically-linked library.
