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Old 01-22-2010, 12:42 AM
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Default Stealth v observation

kcdusk 11-13-2005, 04:20 PM If a PC passes a stealth roll, do you allow the NPC the chance to spot them (observation?) or do you only allow an observation roll if the PC fails a stealth roll?

And vice versa, if an NPC passes a stealth roll do you allow the PC ... in otherwords are you consistant or give the PC's a small advantage?


kcdusk 11-13-2005, 06:26 PM OK I've thought about this.

Originally I was going to have a PC roll v stealth and the NPC roll v observation. Whomever rolled under there asset number by the most would "win" ie would either not be seen (stealthy) or they would be observed. But now I think this makes more sense ...

For a PC creeping up on an NPC, the PC needs to pass a stealth roll. The NPC, because they are not "actively" searching gets no chance to spot a PC who has passed there stealth roll. If the PC failed the stealth roll then the NPC gets to roll v observation.

However, if the NPC is Elite or actively searching (forward observer on task, a sniper or already in place for an ambush) then they do get a chance to see a PC who has passed there stealth roll. But it's a formidable task to spot a PC passing a stealth roll or Easy v a PC who failed a stealth roll.


ReHerakhte 11-14-2005, 04:55 AM This is also covered in the section titled Opposition on page 135 of version 2.2. It covers three types of opposed test but for the example you quoted, you have basically answered your own question in a manner just as suitable as the examples given in the book!




kcdusk 11-17-2005, 05:19 PM How often do Refs make PCs roll for stealth? If your going from A to B and it's a distance of 80 meters and through 3 burnt out buildings, do you make them roll once?

Of do you make them roll 3 times (once per building?).

Getting away from specifics, how do you generally determine how often to roll for stealth?


TiggerCCW UK 11-17-2005, 05:30 PM In the case you mention I would make them roll three times as there are three obstacles.

Usually I only require one stealth roll, possibly because I'm a soft touch as a GM, but if there are multiple obstcles I would generally ask for multiple rolls. I also can't think of a case where one of my players has constantly stealthed for a major distance - they would usually dash from cover to cover and stealth once they got close in, but I'd probably opt for one roll per 100m, as long as there aren't any obstacles.


ReHerakhte 11-17-2005, 08:06 PM Hmm, after reading the latest additions to this thread I am starting to think that maybe my Players are right when they say I am a harsh GM!

I ask the Players to make a Stealth roll for every 10 metres they are trying to be stealthy. The Difficulty Level is dependant on any obstacles, open ground, shadows, dry vegetation, animals in the vicinity etc.

So for 80m I would have them doing 8 seperate checks against Stealth with the Difficulty based on what problems they encounter for every 10m.

I use 10m because the outdoor grid in Ver2.2 is 10m and because it takes a bit of work to be stealthy. You need the patience to take your time, awareness of your environment as well as control over yourself so you don't succumb to the brains natural tendency to go into "flight or fight" mode when confronted with surprises that may occur when your trying to avoid detection (like a flock of pigeons suddenly taking off because you disturbed them).

And I also enforce the 10m idea because some Players would Stealth for 50m in a minute if I let them and I think 50m in 10 minutes is more likely!

And after reading all that again I sound like a right smart-arse!




kcdusk 11-17-2005, 08:31 PM I used to fall into the stealth roll per 10m group. But there were so many rolls that even a bloody cat couldn't sneak around without being discovered because the law of averages meant an 18, 19 or 20 would get rolled at some point and you'd be discovered.

Now I roll once, regardless of how far they need to go. Whether its creeping 50m up to a guard or (just the other night) 1000m through some woods up to a camp site. I figure to keep it simple (1 roll) and consistent (PC's and NPC's get one stealth roll and one observation roll only). I do play around with difficulty though. So creeping 50 up to a guard might be difficult or formidable and stealthing 1000m through woods only average.

But I didn't know if this was now over simplifying things.

If the PC wanted to be stealthy through the 3 buildings I would make it one roll, but it would still take 20 minutes or so. If they decided to creep across the road to another vantage point, then that's one roll.

So its really one roll per "trip", regardless of distance covered.


kcdusk 12-08-2005, 05:18 PM When rolling for stealth, do you roll for each member in the party or do you just use the member with the lowest stealth score?


Antenna 12-08-2005, 09:11 PM Matt Geisler I think havea thought on Stealth vs Obsvervation ....

You can find his work on following URL : http://www.ludd.ltu.se/users/antenna/matt/index.htm



kcdusk 12-08-2005, 10:02 PM Thanks Antenna

I've had a quick scout around that site and while i found some gear i need to spend some more time looking at, i couldnt find anything about stealth or observation.

Could you provide a link to THE page, save me some time :-)


Targan 12-08-2005, 11:37 PM In most RPGs I (and the other GMs in my playing group) use the measurement of "visual distance" to determine both character spacing in marching order (assuming the characters know what they are doing) and as part of the calculation of distance covered between stealth rolls. One visual distance is generally the distance at which two characters can still see each other, and is highly variable depending on terrain, lighting and weather conditions. it is a RL measurement, too, and maintaining a spacing of one visual distance between each character prevents a party "bunching up" and being taken out in a group by an ambush, trap or other surprise event. Obviously, some terrains are so barren, a true visual distance might be miles, such as for a desert foot patrol, so an arbitrary spacing will be decided on by the patrol leader. But for characters patrolling in an urban environment or in dense forest/jungle/scrub, spacing might be as little as only a few body lengths between characters.

For parties which operate with forward scouts and/or flankers, the spacing between the lead/flanking elements and the main body of the party might be several multiples of one visual distance, and this will help reduce the noise problems large parties can encounter. Noise/smell/disturbance of fauna etc can alert observers to the presence of an approaching party long before the party can be seen, so when determining the distance at which stealth and observation rolls must be made, a GM needs to determine the maximum ranges at which observers could possibly detect the party. So if observers have advantages such as an established listening post, have dogs, or are observing from an elevated position, stealth rolls will need to be made at a greater distance than if observers are lax, ill-disciplined, or distracted by noises from their own camp.

I usually conduct stealth rolls for encroachers and observation rolls for observers simultaneously, and translate the results based on the circumstances. So, for instance, the member of the observing side with the greatest potential detection range might fail his observation completely, but a member of the stealthing side fails his stealth marginally, so I might rule that the observers have not been fully alerted but one of their number starts to look at the perimeter more carefully, or the stealthing side startles a bird into flight. A marginal success or near failure observation may result in the observer noting movement, but being unsure whether it was made by a human or an animal, or whether the person seen is a friendly or not.

On some occassions, the scouts deployed by the party in my campaign are so effective that their own side has difficulty keeping track of them. In a forest if there is air movement any stronger than a breeze, movement noise made by a party may not be of concern. Rain is much the same. A character standing upright can be seen from much further than a character crawling or completely prone, but their own field of view is also reduced when down low. I allow characters who adopt a stationary stealth position bonuses if they have skills applicable to improving the camouflage of a position, and generally do not make them roll for stealth again unless they move, or an observer is taking a new angle of approach. The higher a character's skill, the more angles of approach are considered to be covered by their cover (so a charcter with 80% or more in stealth might generally maintain 270 degrees of cover with a successful roll).

The rate of movement of a stealthing character should also modify their chance of success. Assuming a character has 100% stealth, good available cover and the ground they are moving across is not too difficult, I assume they can move at 100% of their normal walking movement rate without penalty while stealthing, with their movement rate reduced by 1% per 2% less than 100% stealth that they have. Movement attracts the eye, so GMs may apply different modifiers depending on the situation.

In summary, say Staff Sgt Barnes and Sgt Elias are moving directly towards one another, at around 2/3 of their normal walking pace, in a tropical jungle and both are wearing appropriate camouflage. It is daylight, not raining, and both are cammed up. One visual distance is probably as little as 15m. Initial stealth and observation rolls might be made by both at around 45m, the range at which they might hear each other moving. Another set of rolls might be appropriate at 30m, the distance at which they might see foliage moving or a shadow of movement. Finally, both would definately make rolls at 15m, when intervening cover is unlikely to be sufficient to hide either from the other.


thefusilier 12-10-2005, 12:50 AM But for characters patrolling in an urban environment or in dense forest/jungle/scrub, spacing might be as little as only a few body lengths between characters.

Or having to hold onto the webbing of the guy in front of them... remembering one extremely unfun night move.


Antenna 12-10-2005, 01:30 AM @kcdusk

check the last paragraphe and second last link



kcdusk 12-11-2005, 02:21 AM Agh, got the paragraph thanks.

So, some great detail on how to do stealth in real life (ie length of sight spacing), but how would this translate to the game?

Are you rolling per person or weakest link or something else?


Last edited by kato13; 02-09-2010 at 01:16 AM.
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