First draft. This is something I want to try using in tonight’s session if it becomes relevant. Adapted from Spectre Operations, 3rd Edition.
When the PCs are trying to do sneaky stuff around an enemy force (or just someone they don’t want to see them), the force starts at one of four levels of awareness. The starting level is dictated by the narrative.
Complacent (1): The NPCs have no reason to expect that anyone is sneaking around their neighborhood and have no particular motivation to be alert. PC Recon checks for stealth are not opposed.
Casual (2): The NPCs may be keeping watch or patrolling their perimeter, but they are not aware of any specific threat. They will investigate anomalous activity, but unless it’s obviously something dangerous or hostile, their general approach will be curious rather than confrontational. PC Recon checks for stealth are opposed normally.
Suspicious (3): The NPCs have reason to suspect hostile activity. Watchkeeping and patrol discipline are tightened up. Sentries will call for backup before investigating anomalous activity, and will move in expecting hostile contact. NPCs receive a +1 modifier when opposing PC Recon checks for stealth.
Alerted (4): The NPCs are actively looking for hostile activity. Anything that gets their attention will trigger a general alert. NPCs receive a +2 modifier when opposing PC Recon checks for stealth.
PCs make Recon checks for stealth normally (i.e., it’s a group check using the lowest base dice in the affected group). Each failure, whether through a natural roll or an opposed check, increases the NPCs’ awareness level by 1 and inflicts 1 Stress on each involved PC.
At the referee’s discretion, if the PCs eliminate all witnesses before they can communicate back to the rest of their group, they may temporarily forestall the increased awareness level. Sooner or later, though, someone is going to find a body or bloodstain or realize Igor isn’t at his post.