These rules assume you are using a full round action to pursue or elude another character who is also using full round actions to move.
Determine Starting Distance.
When the chase starts, the GM should determine how far away from each other the participants are, and make sure this can be reliably tracked.
Determine Travel Distance
Characters who run flat-out can move at 4x their usual combat rate, so each round the chase as a whole will travel the lead character’s run speed.
Note that characters with the run feat can actually move at 5x their combat rate, while usually a character who is encumbered or in heavy armor can only move at 3×.
Even if not a combat per se, a chase is still a skill challenge, so the characters will still be acting in initiative order.
On each character’s turn they will make a skill/ability check to gain or close on their opponent. Treat this as an opposed roll, but only the active character rolls a check, the other character is assumed to roll a 10. For every full five points by which the active character beats the target number, they can gain up to 5 feet on their target, either increasing or decreasing the chase distance as appropriate. An unsuccessful check means that the pursuer is unable to gain any ground, and falls back by 5 feet for every 10 full points by which the check fails.
Note that because these checks are based on relative ability, exact positioning and terrain are unnecessary. You only need mark relative distance. The chase can be assumed to round corners or weave through obstacles (a crowded street, a muddy bog, a raging sandstorm, etc.). A good roll represents cutting a corner tightly or evading obstacles, while a poor check means that the character is hindered by his surroundings.
|Movement Type||Example||Chase Skill|
|Mounted on a Creature||On a Horse, Griffin, Clockwork Steed||Ride|
|Vehicle (Animal Drawn)||Chariot, Wagon, Palanquin||Handle Animal|
|Vehicle (Self Powered)||Airship, Elemental Wagon, Sailboat||Drive or Use Magic Device, as appropriate|
|Character Driven||Swimming, Flying, Running||Fortitude for Running on Foot, but other movement skills might be appropriate.|
Note that the check type refers to the active character. A character riding a horse would use his Ride skill, while an unattended horse would use its Fortitude.
These modifiers affect the character’s Chase score (and therefore the opponent’s DC)
|Faster Base Speed (including terrain penalties)||+ the Difference|
|Heavy Armor or Encumbrance||-10|
|Better Maneuverability (Flying only)||+10|
It is possible to multi-task while chasing while mounted or driving a vehicle and also perform a standard action, within reason -you could make an attack or drink a potion, but scribing a scroll or picking a lock would be too involved. Attempting to do this grants a -10 on your Chase check, and probably a penalty on your other action as well, depending on the difficulty of the task (using a two-handed weapon is harder than a one-handed weapon, for example). The Mounted Combat feat reduces this penalty by half.