PCs could be chased for a variety of reasons. An enemy could be after them because they are escaping a jail. A wildly powerful creature might be chasing them to collect a stolen relic. Or maybe a giant boulder is rolling down on them in a small corridor and there are obstacles/traps to deal with along the way. No matter what the scenario, there needs to be serious threats of an overwhelming force on the player's tail which would likely result in death forcing them to run. 

It is important to take a quick moment and note the player psychology of chase scenes. It has been my experience that a player will ONLY flee if they are well aware that imminent death is on the line. They need to know that the stakes are way above their heads, otherwise, there is likely the belief that they could stand and fight with the possibility of winning because they are ‘heroes’ and Game Masters don’t make it a habit of killing their characters. They also will have the built in belief that the all knowing and kind GM balanced the encounter with a possible winning outcome if they only solve the puzzle correctly. By smashing such beliefs to pieces right out in the open, only then will survival by fleeing be the only possible solution.

Mechanics of Being Chased

Every scenario uses spaces instead of a specific distance to make math easy. For D&D 5e purposes, each space could be considered approximately 30 ft. which works nicely with most movement scenarios. Round all movement to the nearest 30 ft. to avoid any complications. Enemies are always 2 spaces behind at the start and move one space per round keeping consistent pressure up. The players will have 3 basic choices each round. They can stand still and hide in hopes that they are bypassed or not attacked (for some reason). They can move 1 space each round and attempt an action that might help the group or stop/avoid an obstacle. Or they can instead dash like their life depended on it, because it does (otherwise there would be no threat). All spaces have an obstacle event and a free space with no critical choices to make. While each space could have an obstacle, the closer you put them together, the easier it might be to sprint through the entire scenario without ramping up the tension or the characters blow through the entire scene too quickly.

Enemies will always make chase by moving 1 space at a time making it fairly easy for the PCs to outpace them. For this reason, it is important to have a ranged action on their side to keep up tension throughout the entire scenario. This could be accomplished through the use of a fixed item like a ballista, caster in a protected spot slinging spells, or some environmental action like lava flowing and spewing flaming rocks. If dealing with lower level characters, ranged actions can easily be removed, reduced, or used selectively against only 1 character instead of all characters. 

While there should be at least 3 obstacles or decision spaces, there should be no more than six obstacles. If you do more, the entire process becomes lengthy and you have more to design. After six spaces, there would be quite a bit of distance between the threat and the fastest successfully sprinting PC and the slower ones would still be dealing with obstacles.

Should a scenario last more than the amount of rounds you have planned, you can return back to the Dungeon Master’s Guide which describes that a creature can use the dash action in a successive number of rounds a number of times equal to 3 plus their Constitution modifier. After that they must make a DC 10 Constitution check or suffer one level of exhaustion. 

Start by rolling initiative allowing the players to act before the enemy which happens at the end of the round. See the diagram below for a representation of how it works which can be used as a visual tracking sheet.

1. Obstacle 1, Free Space 1 (approx. 60 ft.)
2. Obstacle 2, Free Space 2 (approx. 120 ft.)
3. Obstacle 3, Free Space 3 (approx. 180 ft.)
4. Obstacle 4, Free Space 4 (approx. 240 ft.)
5. Obstacle 5, Free Space 5 (approx. 300 ft.)
6. Obstacle 6, End Space 6, (approx. 360 ft.+)

Meaningful Obstacles

Obstacles are all about risk vs. reward. At each space, you are testing the PCs skill sets against their value of their health and fear of death. In the most simple of decisions, you are sacrificing gaining distance for potential cover from a threat. Obstacles might include: 

• Find some cover (such as hiding behind a structure or diving into a ditch) moving 1 space which will avoid being attacked at range or dash 2 spaces and stay exposed
• Carefully move 1 space through thorns reducing damage and skill check requirements or dash 2 spaces through requiring a more difficult skill check and potentially causing damage. An alternative action might be having the players take the time to cut through the thorns making it easier for other players
• Dash 2 spaces around a large animal cart and potentially get trampled or move slowly around moving only 1 space. An alternative action might be attempting to calm the animal so that it doesn’t spook and cause trouble for others
• Speed through fire and get burned moving 2 spaces or navigate through the flames finding a way not to get burned making a check easier. An alternate method would be that a caster could use magic to spray water dousing flames
• Jump across a gap requiring a skill check at high speed moving 2 spaces or slowly climb through for only 1 space. Failure could push the players back to the start of that obstacle or put them in a pit of sharp objects. An alternate idea would be if the player choose to find a log or some other large object to bridge the gap
• Swiftly wade through a body of water resulting in 2 spaces with a skill check to not get stuck/pushed or take the time to find an alternative more shallow route across. An interesting alternative might be to swim underwater completely avoiding ranged attacks.
• Climb a wall/cliff that needs to be scaled. Failing a skill check could keep them stuck at the bottom. Faster players could fashion a rope at the top making it easier for other players
• Players uncover another enemy, summon a creature ahead of the PCs, or discover a scared animal that effectively stands still making opportunity attacks against anyone that moves past

Other Player Actions

There may be a scenario in which the player can choose to use the environment or cast a spell to delay enemy movement or sight. This creativity should be rewarded because after all the player is choosing to sacrifice a space of movement to dramatically change the terrain. The entire idea is to make decisions and drain important resources that create a dynamic and high intensity scenario. For instance, a player could:

• Push a boulder down the hill at the enemies which may reduce their speed, however, players downhill would now need to make a skill check to avoid being hit as well
• Choosing to cast a spell behind themselves to slow or do damage as the enemies are in pursuit. As a result, both players and enemies would now have a new obstacle to deal with
• Placing caltrops or ball bearings down to slow or cause damage to enemies

PCs Are Chasing

Being chased is not the only scenario that is likely to pop up in your campaign. A humanoid that has betrayed the players or stolen an important artifact might also turn into the players chasing the enemy rather than the other way around. The previous scenarios can help inform example ideas, but the method is not completely backwards compatible. 

In many scenarios, an enemy has lost the courage to continue to fight and is attempting to escape the deadly wrath of the players. Notify the players that this is a new event and explain that there is a slight theater of the mind mechanic that you are going to apply. Successfully winning the scenario will be for the players to keep up with their quarry. 

Enemies will often be inconveniently next to the players and decide to bolt resulting in an immediate chase which is why using theater of the mind is important. For this reason, we will have to manipulate the action economy to benefit the enemy’s surprise action. It is important to note that an enemy next to the players could easily mean general proximity, not necessarily an exact spot for purposes of game mechanics. An enemy will always gain 2 spaces of movement plus an action to generate an obstacle. As the enemy sprints, they might:

• Summon a stationary creature that attacks passing PCs
• Spook a mount that causes possible trampling or slowing of the pursuer
• Cast a spell that causes damage and slows the PCs down
• Drop ball bearings or caltrops to cause damage and slow the players
• Pull down a rickety building or blast a tree/rock slide toppling it placing it in between or on top of the characters
• Cast a spell similar to sticky webs, thick briars, or some other version of magic that slows the players down
• Hide action in a crowd to help confuse the PCs causing them to use an action to study the crowd (slightly different than turning a corner and hiding permanently)
• Climb a building or jump a gap placing a terrain obstacle in between them and the players
• Drop a potion with poisonous gas in it that expands into an area
• And if you really need the enemy to escape, they summon or steal (or otherwise acquire) a mount that can put serious distance between the two groups

Players will likely be casting spells at distance to slow the enemy’s speed and stop them in their tracks. This is balanced by the fact that the quarry can move swiftly and act as well on the same turn helping the enemy to slow the players. If at the end of 6 rounds (or 6 obstacles) the PCs are still on the tail of the enemy, it is time to narrate their capture as they become too exhausted to continue the escape. 

Speed Complications

Any creature that has significant speed beyond the other players will create a serious advantage to their side. That is typically a result of having either some vehicle, mount, or other method of speeding past all other characters such as a teleport. This can be both realistic and rewarding, but to make it more fairly balanced, you may need to increase or decrease the distance depending on if the players are the quarry or pursuer. 

Putting It All Together

Let’s say that a wizard tricks the players and steals an important relic from the PCs in a town. The players waste no time taking chase upon the sight of his treachery. Give the enemy the first turn to create immediate tension of loss. The wizard will:

1. Drop a bottle of greasy liquid to slow the PCs and quickly dash or teleport 2 spaces ahead of the PCs. One player chooses to go around the grease, another slips. Several players are able to catch up. Another player shoots the enemy with an arrow reducing his health
2. The wizard then sprints forward moving 2 more spaces ahead and casts a spell creating a fiery mess for the players to navigate through a burning building. Several stronger players brave the flames sprinting through and continue to keep pace.
3. The wizard begins to tire, so he bolsters one last burst of energy moving 2 more spaces and attempts to lose the PCs in the crowd. By this space, he knows the players are too strong to escape from and they spend time looking for him in the crowd
4. In a desperate attempt to make some distance, he mounts a horse and starts speeding away. Then the party caster loses patience and casts a spell to freeze the evil wizard in place allowing his party to catch up.

The players have won! Or have they? The wizard quickly summons a massive demon that turns the tide resulting in the players sprinting for their lives. The wizard makes ranged attacks while the PCs retreat and his demon demon rampages 1 space of movement per round. At obstacle:

1. The demon summons more demons ahead the players creating a new obstacle that attacks the players as they sprint passed 
2. The demon casts a darkness spell and the players need to slowly navigate around it (1 space) or risk running directly into a hard object (such as a building)
3. The players need to go back around/through the blazing structure from the previous scenario showing them that their actions are still relevant
4. The PCs decide to duck into a building to avoid any further demonic wrath

Another Chase Scenario

Here is another scene I used in my own game with 9th level characters who had several casters at their disposal. They had alerted an outpost of Dark Elves in the session prior and had escaped their wrath until this event. I also needed to move through a set of cave tunnels quickly and thematically, so I decided to overwhelm them with a horde of Dark Elves summoning Demons at the same time. Pushing them through the caves solved both problems and the writeup looked something like this. 

Scenario Overview. Dark Elves summon a Marilith and command it to attack the PCs. The Dark Elf archers prepare their bows to shoot players in the open every round. The Marilith moves one space per round following the PCs. After 6 rounds, the players will be able to quickly rest, but then the Marilith teleports into their area for an epic battle.

1. Space 1 Obstacle. The Marilith Demon is hot in pursuit of the players and the Dark Elves prepare to release arrows from their bows at visible player’s backs. In obstacle 1, players can:
1. Move forward 1 space and hide behind a rock avoiding being targeted by Dark Elf arrows. The problem is that the Marilith catches up to the PC(s) and makes some devastating attacks at them
2. Sprint 2 spaces staying out in the open. Poisoned arrows from the Dark Elves target each PC in the open
2. Space 2 Obstacle. The summoner of the Marilith, still within distance, conjures flame cyclones in front of the PCs blocking portions of the passage. Players must avoid the cyclones or run through them. In obstacle 2, players can:
1. Carefully navigate through the fire the players gain advantage on dodging the fire moving 1 space. The Dark Elves are still able to fire arrows at them
2. Find a pit/crevice to avoid arrows from archers, but still have to deal with the flames overhead moving only 1 space.
3. Sprint through the flames moving 2 spaces. Both poisoned arrows and fire could damage the PCs
3. Space 3 Obstacle. The cave descends revealing a pit on one side making falling a serious problem if the players do not navigate the thin ledge on the other side. Sharp rocks lay at the bottom. In obstacle 3, players can:
1. Move 1 space slowly gaining advantage on not falling into the crevice. Standing players will still have arrows shot at them by Dark Elves
2. Dashing results in disadvantage on the check to traverse the ledge. Failure results in loss of the dash and falling into the crevice
4. Space 4 Obstacle. The cave turns around a bend and the sounds of Dark Elves behind the players are starting to become distant echoes. The players should feel comforted that they might escape. Then the cave opens up into a larger cavern with thick webs sticking from ceiling to floor. Players must avoid the webs or become restrained by them. In obstacle 4, players can:
1. Carefully navigate the webs moving 1 space as they cut through thick spider webs. They gain advantage on their check to get through
2. Sprint gaining 2 spaces, however, they gain disadvantage on their check to get through the webs
3. Burn the webs resulting in smoke inhalation and heat damage to others that pass through as the webs burn for the next minute 
4. Anyone stuck in webs gets attacked by a lurking spider at the start of their turn
5. Space 5 Obstacle. After the webs, the cavern thins into a small opening barely big enough for a medium sized creature. The opening reveals mushrooms all over in an erratic display of colors. If disturbed, they explode into a puff of poisonous dust for 1-minute. In obstacle 5, players can:
1. Players can attempt to avoid disturbing the mushrooms by moving only 1 space. Failure of the check causes mushrooms to burst in a poisonous cloud which affects anyone within the space 5 obstacle area causing damage 
2. Players can sprint 2 spaces through and make their check at disadvantage. If the cloud has already been detonated, they must make a check to ward off the effects of poison being inhaled
3. Wind can be blown to push the poisonous cloud away
6. Space 6. Players should now feel safe and quickly have a round to deal with any ailments that they encountered since fleeing. Once all the players reach the final cavern, they roll initiative to face the Marilith and a climactic final encounter to the scene. In this case, there was no obstacle because I had deadly combat at the end to keep the thrill going.

It should be pointed out that in play players cruised through many of the obstacles even quicker than I had anticipated. Spells like teleport, wall of fire, and other magic items helped them breeze through some of the obstacles. I didn’t take their winning tactics away from them, rather, I used other methods to continue to create tension (such as the wizard and demon both teleporting). The final result was that they had more health resources at the end to deal with the encounter, which was still an amazing build up.

Conclusion

And there you have it! As you can see, there is flexibility in the system which can work with both terrain as well as character abilities. This process aims to create a lot of tension by slightly sidestepping the standard movement mechanics to add in some creative, thematic, and imaginative aspects that no map could accurately plan for.