Tony Vargas
Legend
I'm not sure I've seen any game mechanics handle that. I remember plenty of old modules going into that kind of detail (if the orc in area A rings the gong, 2d8 orcs from area C arrive in 1d4 rounds, &c....), but it's all arbitrary (and I can't think how a system would approach something like that, it seems to be firmly in the DM's-judgement realm).The skill challenge is not bad. My other observation is that there is both tactical and OPERATIONAL levels of surprise. The latter is just as important and 4e can certainly handle THAT. In other words getting the jump on the orcs guarding the entrance is one thing, they're likely to be wary, they're certainly armed, and maybe at best you reduce them to a minor threat by a totally unexpected attack. The ORC LAIR ITSELF is another thing. How many of the orcs are awake? How many have weapons and armor to hand? How many are even present in the lair when you make your assault? How effectively do they rally and how quickly can they muster their forces, identify the axis of the attack, determine its strength and nature, and mount an effective response? If you're FAST ENOUGH and achieved tactical surprise at the entrance, well, they might not really offer a ton of resistance overall. So an attentive DM can manage that aspect of things to provide decision points and incorporate tactical thinking. 4e certainly CAN handle that, though D&D traditionally has shied away from this whole aspect due again to the wide range of challenge level that might result depending on good or bad choices.
That's exactly how I wouldn't want to do it, since it captures how the player reacts to limited information, when it's the character that's supposed to be being modeled.Well, its true, PCs have perfect 'presence of mind', at least in most systems such as D&D. You COULD enact a sort of 'fog of war' kind of thing using limited information, but it would be a little weird, more suited to systems like DW that are pretty abstract and lack mechanics covering positioning and whatnot.
So if mechanics were to cover some kind of 'fog of war' effect, it should be modeled and resolved based on the character - from simple penalties to more involved conditions.
A related thing that'd be cool is some meaningful 'covered' condition. The old sword to the throat or held at gunpoint, another trope D&D has never done well. Just having to weather an attack is not much of a threat to most D&D characters. But if they can get the drop on you, maybe they can do a /lot/ of damage (like you are reduced to your bloodied value, /then/ take a critical hit), unless you (or something) distracts them or gives you a chance to change the situation. In 4e, that'd be a fair thing to declare when you've reduced an enemy to 0 - you've forced a surrender and have them at swordpoint, or something along those line. But dropping to 0 is not that likely without focus fire.