Searching Rules

The following pages detail the hexagonic searching system, a system I have developed to make searching in any game system easy and somewhat realistic.

General Premise

The basis is this system was developed for Powers & Perils, which uses a hex system of movement. It can be applied equally well to many other game systems.

There are three basic parameters to consider when using any searching method: Search Area, Visual Area and Travel Speed.

Search Area

is the area to be searched for the object. This could range from tens of feet (looking for a hidden person) to tens of miles (combing the countryside for a lost temple).

Visual Area

is a value determined by the referee based on three variables: Size, Line of Sight, and Cover. In general, the larger the object, the larger the radius in which you can see it (compare looking for a man to looking for a house in the same environment). Second, if there are lots of breaks in your view (hills, large trees, lost of brush) the visual area will go down a lot. In areas of little cover (flat, featureless plains) the visual area will go way up. Finally, if the object in question is bright orange in a green forest it is visible at a greater distance then if it was green and covered in vines, leaves, etc. The referee must decide for him/herself at what range a character or NPC could reasonably see the object or person being searched for given all the above conditions. Other senses should be used if they have a better range. (thus, if a hunting Broo can see you within 10m, but can smell you within 50m, use the smelling range.)

Travel Speed

is the speed of travel in the search. The idea behind this is the fact that faster searchers can search an area more rapidly, thus searching more area per time period, thus giving a higher chance of finding the object in question in the time period.

There are two ways of using this system: Time based and probability based.

Time Dictated

A search dictated by time means "for a given time period, what is the probability of finding the searched object?" The variables are:

a, the radius of the search area in units.

v, the radius of the visual area in units.

t, the total time of search.

h, the size of a "unit". This is based on the game system and the situation. For P&P this is most likely 10' distances for combat or short distance situations, 100'-1 mile for longer periods of time.

s, the speed of the searcher. This should be based on the units per standard time (For P&P, the average PMR or MR)

Using these five values, the formula below will return the base chance of being in a position to find the object being searched for. This assumes the target is stationary and the searchers are being careful to comb the entire area. If the searchers are sloppy or not very careful, divide the base chance by three. If the target is moving, the base chance may be reduced by one-half.

50 s t (v+1) / a h (a+1) 

EXAMPLE - Sheven is on the run from a large and very angry Bear Tonah. Luck was on his side when the Tonah was temporarily blinded by the thrown sand, but the Monster is on his tail again, out for blood. Sheven runs over the hill into a large patch of forest surrounded by grassland. Deciding to trust his abilities to keep hidden in the woods, he heads for the brush and hides in it's interior just as the very pissed Tonah comes over the top.

Thorg of the Broken Spire, looking for the little man who dared to steal from him, spots the island of woods and pauses. He sees no movement in the tall grasses, so he assumes the little wart of a human must be in the woods. Keeping his claws ready, he strides into the woods to find him.

Let us say that each unit is 1" (10 feet, h=1). The forest-island is about 150" across (a=75) and Thorg has an MR of 12 (PMR=3, thus s=3). Given the high amount of cover, let's say Thorg has to be within 5" of Sheven to have a chance of spotting him (v=5). Finally, Thorg is tiring of this game and quite frustrated at him getting away, so he will not be quite as careful. We will assume 1 turn per phase (t=1). Sheven will not try to move. Totalling it up, poor Sheven has (50x3x1x(5+1))/(75x1x(75+1)) or a base 16% chance of Thorg being in a position to see him each phase. Because we said Thorg is not being careful, this is divided by three to 5% each turn.

Each turn the referee rolls 5% or less, and Sheven sees Thorg stomping around his hiding place, both Thorg and Sheven make ambush rolls. If Thorg's fails and Sheven succeeds, or if Thorg's success roll is lower than Sheven's (i.e both have a 45% chance, but Sheven rolls a 40 and Thorg rolls a 13), he could still have another try at reduced chances (see below) The referee could (and should) really play this up ("Thorg is almost breathing down your neck! Do you sit still and pray, or bolt?").

What happens after finding the area? If the searcher is being careful, it means he is trying not to search covered area again. Divide the finding chance by TEN. If he is being careless, divide it by TWO. If he is being VERY careless (just stomping around), divide it by THREE.

Increasing the number of searchers will multiply the success probability. In this case, unsuccessfull finds reduce the chance by TWO if careful and not at all if careless. Sometimes it takes an army just to search a good sized area in a given period of time.

Probability Dictated

A search dictated by probability means "For a given probability, how long will each search period be?" The variables are:

a, the radius of the search area in units.

v, the radius of the visual area in units.

n, the probability of success, from 1% to 100%.

h, the size of a "unit". This is based on the game system and the situation. For P&P this is most likely 1" distances for combat or short distance situations, 10"-1 mile for longer periods of time.

s, the speed of the searcher. This should be based on the units per standard time (For P&P, PMR or MR)

Using these five values, the formula below will return the time required for each searching period. This assumes the target is stationary and the searchers are being careful to comb the entire area. If the searchers are sloppy or not very careful, multiply the time by three. If the target is moving, the time is DOUBLED.

Using these five values, the formula below will return the time required for each searching session.

a h n (a+1) / 50 s (v+1)

EXAMPLE - Sheven and company are looking for Thorg's hidden lair. They know the rough area, but not the exact location. After studying Thorg's habits (from a distance) and from Sheven's information, they have narrowed the search area to an area 2 miles across (a=1056"). They are searching a rugged area, so the referee decides that they travel only at an rate of 1" per phase, or 1200" per hour (s=1200). Units are obviously in 1" (h=1). However, the terrain is very rough and his cave is very well hidden, so the visual distance will be quite low. If they have 5 party members, they could either split up and search separately (possibly a bad move; Sheven advises against having a one-on-one with Thorg) or search as a spread out group. They decide on the latter. A person must be within 10" to see his cave, but they are combining to form, in effect, one "entity" with an extended searching range. They decide to be no more then 10" apart (5" to the center), so the visual range is now 15" (v=15). Finally, the referee decides to give a base chance of 25% (n=25). Putting it all together, the time per search roll is(1056x1x25x(1056+1))/(50x1200x(15+1)) or 29 hours. At a rate of 10 hours per day for searching, this is 3 days per search roll.

Had they split up (the cowards!) they would have had a collective time of of (1056x1x25x(1056+1))/(50x1200x(15+1))/5 or 5.8 hours (1 day) for each search roll. The first roll is always given at 1/2 the listed time; all subsuquent rolls are made after the full time period.

Burton Choinski