GM Core Chapter 4: Subsystems Chases

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 soldier who's terrible at Stealth a way to help. The group can help cover for a character who's 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

Sometimes circumstances might require you to run a chase where the PCs are each progressing individually, rather than as a group, such as if they get split up. The danger therein is that a player can easily become frustrated if their character is stuck at an obstacle where it's extremely difficult to succeed at either choice, and no allies can help them. In these chases, it's best to allow even a single success to be enough for a character to progress to the next obstacle, and have a critical success give the character a +2 circumstance bonus on their first check against the next obstacle.

Setting Obstacle DCs

Source GM Core pg. 215

When you set the DCs for an obstacle, you'll typically be using simple DCs. Use a proficiency rank that's generally appropriate for the PCs' level if you want the obstacle to be a significant obstacle. As noted earlier, you'll typically want to select a couple different ways the group can get past an obstacle. At least one check should have an easy or very easy adjustment, while the other check should have a standard or hard DC. In some cases, you might use something other than a simple DC; for example, if a specific NPC has put up a wall of steel, you would use their spell DC. This might result in some pretty tough DCs or even impassable obstacles, so use this carefully!

If a PC improvises a different way to get around an obstacle from what you planned, set the DC just like you would normally when picking a DC on the fly. Don't worry about adjusting the DC to be easy or very easy because the PC is likely to be good at the skill they've chosen.

Shortcuts and Split Paths

Source GM Core pg. 215

You might want to build a chase with multiple paths that split and rejoin so you can have a shortcut (with easier DCs or fewer obstacles) or paths that appeal to different types of characters. For instance, one obstacle might allow a PC who critically succeeds at a Perception check to find a faster path through an air duct, without the obstacles of navigating a busy nightclub. This can be fun, but it can also split up the group. Familiarize yourself with the Solo Chases sidebar to make similar adjustments for a divided group.

Ending Chases

Source GM Core pg. 215

Once you have the obstacles, decide the end conditions. Chases often end when the pursuer reaches the same obstacle as the pursued, leading to a combat encounter or other scene. However, it's less clear when to end a chase otherwise. It's typically best to have an obstacle that ends the chase with the pursued character getting away, as long as they overcome the obstacle before being captured. This is usually better than ending the chase after a certain number of rounds because reaching a hideaway makes more narrative sense and because you might not be able to predict how far the pursued characters move in those rounds, making you run out of obstacles. You can also end the chase in favor of the pursued characters if they ever get a certain number of obstacles ahead of the pursuers (typically three), as the pursuers simply lose the trail. You should still have an end point to the chase, though, in case that never happens.

Types of Chases

Source GM Core pg. 215

Chase Down: The PCs pursue adversaries. The PCs go second in initiative since they're the pursuers. Start the enemies one obstacle ahead of the PCs (or at the same location for a short chase), and end the chase if the PCs catch up to the enemies, or if the enemies reach a certain location that represents their safety or escape.
Run Away: The PCs attempt to escape. They'll go first in initiative since they're being pursued. It's usually best to start them one obstacle ahead of their foes and end the chase if they reach a certain location or are three obstacles ahead of the foes at the end of a round.
Beat the Clock: The PCs try to get through all the obstacles before a certain number of rounds pass, such as if the PCs are trying to outrun a natural disaster or race in a timed challenge. The number of obstacles should usually equal the number of rounds.
Competitive Chase: The PCs and their adversaries are both chasing the same thing or trying to reach the same location, and whoever gets there first wins. This works like chase down, except that either party could win. Because there's more than one set of pursuers, you might have the PCs and their competitors roll initiative to see who goes first each round (while still moving all NPCs at a steady rate).