Chases

Chases are a special type of encounter. Each round, the pursued character or characters act first, then the pursuing characters act. Typically, to reduce variance, the PCs roll checks to progress while their opponents proceed at a steady pace, but if you want to emphasize the back-and-forth nature of a particular chase, you could have both sides roll instead. Characters in the same group can act in whatever order they prefer, each taking a turn. A character must act on their turn. If they pass their turn or are unable to act, they're unable to help the group and automatically cause the group to lose 1 Chase Point.

Obstacles

Each obstacle requires a certain number of Chase Points to overcome. Typically, half the obstacles require 1 point fewer than the number of party members, and half require 2 points fewer (with a minimum of 1 Chase Point per obstacle). Particularly challenging obstacles might require more. Typically, there are multiple ways to overcome an obstacle; for example, characters could evade a guard or bribe them to look away. Each approach usually requires a skill check or Perception check, but sometimes a saving throw, an attack roll, or something even more unusual, like casting a certain spell.

On a character's turn, they describe what they do to help the group get past the obstacle. They then attempt any required roll, or perform the required action for a choice without a check. If they attempt a roll, the result determines how many Chase Points the character gains.

Critical Success The PCs gain 2 Chase Points.

Success The PCs gain 1 Chase Point.

Critical Failure The PCs lose 1 Chase Point.

If the means of bypassing the obstacle helps automatically without requiring a check—such as using a certain spell to assist—the PCs typically get 1 Chase Point. You can increase that to 2 if you feel the action is extremely helpful.

Chase Points represent the ability of the whole group to bypass the obstacle. A character who critically succeeds is able to help the other characters continue onward, while one who critically fails needs extra assistance. Players often have ideas for ways to overcome the obstacle beyond the choices you created for the obstacle. If their idea is applicable, you'll need to determine the DC and skill, or other statistic being used for that approach. This is great as long as it's creative, but be wary of a situation where a character who is legendary at a skill tries to justify how they can bypass every obstacle with that skill, such as using Acrobatics to tumble around them all, or the like. You can determine that some tactics just won't work against certain obstacles, or would help only one character without benefiting the rest and therefore aren't all that useful.

Once the PCs accumulate enough Chase Points to overcome the obstacle, they move on to the next. Extra Chase Points don't carry over to the next obstacle. However, anyone who hasn't already taken their turn that round can still take it against the new obstacle. Consequently, the characters best suited to overcoming the current obstacle might act first, since the remaining characters might be better suited against the next one. The number of Chase Points the PCs have can never fall below 0.

Building a Chase

When building a chase, first build your obstacles, and then decide how far ahead the pursued character or characters begin and at what pace the NPCs will move. Having the NPCs clear one obstacle per round is a good rule of thumb, but it could vary depending on the situation, and should especially be slower against obstacles that require more than the typical number of Chase Points to overcome.

Select or build obstacles highlighting a variety of different skills and other options so everyone in the party has a moment to shine. When choosing what skills can bypass a given obstacle, ensure a variety of approaches can work. If you've already decided that an obstacle uses Stealth, selecting Thievery as the other option doesn't really offer opportunities for different types of characters, since those who are good at Thievery are very likely the same ones who are good at Stealth. On the other hand, offering Athletics as an alternative gives a champion who's terrible at Stealth a way to help. The group can help cover for a character who is less capable at a particular obstacle, but it's more fun for players when you present substantially different options for each obstacle.

Use the following guidelines to determine how many obstacles you need for your chase. These numbers assume that the pursued party can reach a certain location to end the chase (as described in Ending Chases). If there's no such escape, you might need more obstacles.

Short: 6 obstacles, about 10–20 minutes of game time

Medium: 8 obstacles, about 15–25 minutes of game time

Long: 10 obstacles, about 20–30 minutes of game time

Running a Chase

When running a chase, narrate the scene and give vivid descriptions of the obstacles the PCs face, rather than just reading off a list of skills and immediately having the players start rolling dice and making checks. A chase is a framework for roleplaying, not just a dice game. Encourage the PCs to describe what they're doing, and how they're helping their comrades overcome each obstacle.

Typically, it's best to tell the players the DCs of the default options, so they can make informed decisions. At the very least, you should indicate the relative difficulty of the clear paths.

Try to make it feel like the PCs are really part of a chase scene, like in a movie. As each side makes progress, describe how they pull ahead or close the gap. PCs far from their foes might hear shouts in the distance. As they get closer, they catch glimpses, and then finally see their quarry in full view once they're on the enemies' heels. Think about how the events of the chase affect the environment as well. For instance, if a kaiju is chasing after the PCs, after the PCs overcome an obstacle consisting of a thick copse of trees, you could describe how the kaiju flattens the trees beneath its feet as it stomps after them.

If the PCs Get Stuck

Sometimes, despite their best efforts, an obstacle will stymie the PCs over and over again. In most cases, after 3 rounds of the PCs struggling with an obstacle that requires the standard number of Chase Points, it's a good idea to just say they found another way around it. If presenting another way around the obstacle just doesn't make sense, such as if a spherical barrier completely blocks the PCs, you might introduce an NPC or other outside force that can help them bypass it, but at a high cost.

Source Pathfinder GM Core pg. 192