Has anyone adapted the Exchanges/Volleys and Scripting mechanics of Duel of Wits, Range and Cover, and Fighting for lengthy sneaks? If so, how did it work out for you?
I personally haven’t done this, and probably haven’t thought of twenty problems that might arise, but I could see it adding some nice tension to a stealth situation. For example, I script to sneak out from behind my cover, while the opposing guard scripts to turn and walk in my direction; I forfeit an action to duck back behind cover. It might have a lot more suspense than a Versus test for sneaking!
That still violates the task/intent breakdown of Burning Wheel. He should have stated what he wanted to do, you should have given him an Ob that’s reasonable based on what he wanted to do, and then he should have rolled to find out how that went. If they ask for too much, you tell them either a really high Ob or that they are asking for an unreasonable thing: sneaking in to the castle, picking the lock on the safe, stealing everything inside the safe, and sneaking out may simply not be feasible based on time/player skills/your vision, and in that case the GM is perfectly in their right to say “you can sneak in and out with a stealth roll, but if you want the stuff in the safe that’s going to be lockpick or something else.” If someone’s trying to just sneak into a Goblin fortress, you should ask them why they are sneaking in and what they want to do there. It’s all good and fine that they want to sneak in, but unless there’s a reason it sounds to me like a Say Yes moment.
Vis-a-vis the Op, if you’re just trying to sneak in and do something, just go with the opposed check (because it’s quick and because sneaking in most likely isn’t the actual focus of the scene). If you’re trying to do something more, Range and Cover with a lot of Stealth positioning tests on the part of the aggressor, and a lot of Perception/Observation tests on the part of the guards is probably the way to go. Remember that just because we (the players) know that there’s a dude sneaking in and that the guards are opposing them, doesn’t mean the guards know in-fiction. As far as they are concerned they may just be hearing things and feeling a little paranoid.
Actually, buying “progress” through a single Stealth roll is an example of a graduated test, which is supported by the rules. It’s just like having a player roll to see how much knowledge they can dredge up in a village. Set the Ob at 1, and each success gets you something.