AbdulAlhazred
Legend
Lets look at Dungeon World. The GM is encouraged to carry out preparation, which consists of SOME mapping (with holes, meaning the maps/descriptions should be fuzzy enough to allow for elaboration during play). The GM can prepare 'Fronts', which are basically just groups of bad guys or other 'forces in the world' that may oppose/threaten the PCs. Dooms can be established for them which will trigger on basically a timer.So how, then, in that different set of procedures can a GM have the opposition proactively do anything to stop/hinder/gain an advantage over the party before the party interacts with them? Or is the opposition supposed to be passive (or. even, non-existent) until the PCs meet it?
Take my example of the spyholes above, where the opposition were able to keep tabs on us and react to what we were doing almost before we did it. How in your set of procedures can the opposition a) become aware of our presence without us realizing it and then b) use an unknown-to-the-PCs (and players) feature of the setting in their attempt to thwart us?
The GM is NOT empowered to say something like "no, you cannot find anything useful here because there IS nothing useful." If a player makes a DR check, and is owed an answer, the GM MUST provide one, but it can be anything which is compatible with the agenda and practices of DW. Presumably GMs will not generally contradict their own prep, but they MAY HAVE TO DO SO. GMs also frequently 'make moves', which is how new fiction is often introduced.
So, if the GM had in mind that the PCs were being spied on via this set of secret tunnels, he can make moves consistent with that. He can decide to only reveal these tunnels when it is dramatically interesting for him to do so. Frankly, he's probably got MORE POWER here than a classic Gygaxian DM who probably should not keep these things concealed beyond the point where the PCs fulfill preestablished (or rule supplied) conditions for finding them. The DW GM is probably going to find that his agenda and practicality dictate introducing this fiction to the players under certain conditions, but its not really mandated. And if he chose to supply some other explanation for the enemy's foreknowledge (like revealing the existence of a spy in the party) instead, then maybe those tunnels never existed at all!
My point is, it is quite easy to surprise players and characters in DW. Now, you MIGHT actually, in some other games, keep this secret at all. Maybe the players know, maybe they even invented this explanation themselves (that could actually happen in DW, but the GM would probably have to invite such a revelation). I think generally players and characters have similar knowledge in most games, but it really isn't a requirement.