I don't like the idea of a simple skill roll to search for traps, but that doesn't mean I like or use the extreme pixel-bitching approach to traps, either. I'm probably just a little more detailed than Brendan describes for his own technique. If someone says "I search the room", I ask "how", but all I'm expecting is general details: Do you enter the room, or stay outside? If you enter the room, do you just blunder on in, walk normally, or creep along slowly? Are you just searching visually, or are you touching things (with or without a 10-foot pole?) And if you're touching things, are you actually tapping or knocking, or are you moving things around?
So, basically, it breaks down to speed and direction, stance, senses and tools used, and any changes to the environment made. I assume, unless told, that you do everything that could be included in the general description of what you tell me, without going too far. You stand in the doorway and do a visual search? Then anything that *could* be seen from where you are standing is seen, no roll necessary, and no weaseling out by saying "you didn't say you were also looking at the ceiling". I figure that these are the basic search procedures:
- Blundering In: You enter the room without searching. This always applies for those fleeing monsters, unless you say otherwise.
- Careful Entrance: You enter, but not necessarily quickly, and look at stuff as you enter. This action stops as soon as you spot anything out of the ordinary (no roll needed, as long as it's visible and not hidden.)
- Stop, Look and Listen: You don't enter the room, so no traps triggered by movement or pressure will go off. Anything visible or audible -- or smellable, or detectable by any other sense that works over distance -- is automatically detected.
- Cautious Test: You use a ten-foot pole or similar technique to test from a distance. Discovers a few things you'd miss by the previous techniques. If you also add tapping with the pole, you discover hollow spaces as well.
- Thorough Test: You touch what you're searching, everywhere. Discovers hidden catches, buttons, and the like.
All of these assume you are standing up, bending and crouching only as needed, and make no changes (nothing is moved or opened.) A careful entrance assumes you look under things, on top of anything you can see the top of, behind anything you can see behind, and around every corner you can look around. The first time you would notice something out of place or out of the ordinary, I describe that, and assume you stop until you tell me what you do next. If you have to move something or open something to continue a search, I ask if that's what you want to do.
Richard's comment brought up the topic of expectations. What do I lead players to expect, and how do I want them to behave? I think that depends on the general type of location.
- Wilderness has natural dangers that may function like traps, but nothing too devious in most cases. The expectation is that adventurers will proceed carefully and stop, look and listen when discovering something new.
- Inhabited lairs are going to have alarm traps and sentry points, plus a few check points where you have to enter the area in a certain way to avoid injury or capture (like the one-way corridors.) If they have time and resources, there will also be branches where you have to chose the correct path or walk into a trap. The expectation is that adventurers will scout a known inhabited area and try to observe the behavior of the inhabitants. Once scouted, careful entrance would be the norm, with cautious testing of missed areas and treasure containers.
- Ruins and abandoned lairs will have pits, the occasional untriggered lair trap, and some natural hazards from crumbling structures. Untriggered traps would be dealt with as for inhabited lairs, but there's a chance the trap simply doesn't function, due to age.
- Legendary vaults and tombs will be known to have escaped looting, somehow, so this is where the truly devious stuff would be. Adventurers are assumed to have picked up a few rumors about the scary dangerousness (and tempting riches) of such a place beforehand, so the expectation is that this is where the adventurers should be paranoid.
A megadungeon is basically an underground wilderness with individual areas that stand out. Most of the time, the adventurers would worry only about being spotted by dangerous creatures, missing interesting discoveries, or blundering into something obviously different. Within this framework, there will be lairs (inhabited or not) and occasional legendary areas.