There are two cases of pursuit and evasion of pursuit. The first is in underground situations, and the second is in outdoor settings. There are various special circumstances which pertain to each case, so each will be dealt with separately.
When player characters, with attendant hirelings and/or henchmen, if any, elect to retreat or flee from an encounter with a monster or monsters, a possible pursuit situation arises. Whether or not pursuit will actually take place is dependent upon the following:
Pursuit will have 3 separate cases:
1. The pursued are faster than the pursuers: Unless there are extenuating circumstances, such as a ranger NPC or an invisible stalker or a slithering tracker pursuing, then pursuit will end as soon as any one of the following conditions is met:
2. The pursued are of equal speed to the pursuers: As in case 1. above, pursuit will end as soon as any 1 of the following conditions are met:
3. The pursuer is faster than the pursued: The pursuit will be broken off only if one of the following occurs:
There are several circumstances which will affect the pursuer. These are:
Barriers. Physical or magic barriers will slow or halt pursuit, i.e. a locked portal, a broken bridge, a wall of fire, etc.
Distractions. Actual or magic distractions will be from 10% to 100% likely to cause pursuit to falter or cease altogether. For example, a dancing lights spell moving away from a fleeing party which has extinguished its light sources might distract pursuers, just as a phantasmal force of a strong helper joining the pursued might cause the pursuers to cease pursuit. Similarly, if the pursued passed through or near some other creatures which would be hostile to the pursuing force, or at least not friendly to the pursuers, then it is quite possible that the creatures passed through and the pursuers would become embroiled.
Multiple Choice. It will most often come to pass that the pursued take a route which enables them to cause the pursuer(s) to have to make decisions as to which direction the pursued took in their flight. Thus, at a branching passage where there are 3 possible ways which could have been taken, there is a basic 2-in-3 chance that the pursuer(s) will take the wrong passage. Likewise, if there are a door and a passage, there is a 1-in-2 chance of wrong choice. This base chance assumes that the pursuer cannot see the pursued when choice is made, that sound does not reveal the direction of flight, that smell does not reveal direction of flight, nor do any other visual, audial, or olfactory clues point to the escape path. As DM, you will have to adjudicate such situations as they arise. The following guidelines might prove helpful:
Building Interiors. Treat these settings the same as one underground, as applicable.
If it is discovered that a pursuit situation exists, and the player-party elects to evade rather than confront pursuers, then record the relative speeds of pursued and pursuer. Move the pursued party as many 10’s of feet as their slowest member is able to travel, and likewise move the pursuing party as many 10’s of feet as its fastest member can travel, noting positions of slower members, if any, as well. This movement is accomplished on the map, of course.
Three such movement phases are (for game purposes) equal to 1 round.
At the end of any movement portion where any number of the pursued party is within 10 ft. or less of any number of the pursuing party, confrontation must take place between the concerned members of the parties. (At this point the remainder, if any, of the pursued party may elect to stop flight or continue evasion attempts as they wish.) Also, at the end of each movement portion it is necessary to check the 3 separate Pursuit Cases and any Modifiers to Pursuit to see if the pursued party has succeeded in evading the pursuers. Keep track, not only of the route of flight, but also of the amount of game time so spent, as some pursuit will automatically cease after a set period without confrontation.
Mapping During Flight. No mapping is ever possible. Give no distance measures in moving the pursued. Give no compass directions either!
Pursuit in the outdoors is generally similar to that in settings underground or indoors. The 3 general rules of likelihood of pursuit apply. However, pursuit will certainly continue until evasion is successfully accomplished.
In outdoor settings, evasion is accomplished in a different manner, the variables being the relative speed of movement and size of the parties concerned and the type of terrain over which pursuit takes place. Available light is also a factor.
Upon encountering creatures from which the player-party flees in order to evade, determine if a condition of Surprise exists.
If the player-party has surprised the creature encountered, evasion is automatic.
If no surprise exists, then follow the procedure below. If the party encountering the creatures is surprised, then no evasion is possible, and confrontation is unavoidable.
Continuing pursuit requires on evasion check every game hour. After the initial check each game hour, another must be made just as is initially done, with the added stipulation that any result of 0% or less indicates immediate confrontation and no further chance of evasion.
[See also Appendix A—Conditions, Fatigue & Exhaustion]