Catch That Man!
When your party consists of deadly barbarians, mages, and fighters armed to the hilt with magic items and implements of war, most people would rather run than face you. It's not surprising that this causes problems of its own. After all, in a dungeon you can take your time, sweeping every room for monsters and treasure, but in a city or in the wilds, enemies will almost always run rather run than die, especially if murder isn't their prerogative. As a DM, don't forget that enemies can flee if the tide turns against them or if they would rather not fight at all. But how should we handle chase scenes?
How To Do Chase Scenes
The Dungeon Master's Guide contains one example of how you can run chase scenes, but I have a more effective, and certainly more concise, means of running them. This is by no means a unique ruleset; many tables use similar rules. Consider this one such example of those rules, and hopefully a good representation of them.
Rank. Each character in a chase has a rank, which is a number of rounds the character is behind the lead runner. Lower ranks mean you are closer to the lead runner.
Round. The chase happens in rounds, during which each character encounters and obstacle and makes an ability check to overcome it.
Obstacle. Characters will need to overcome these in a chase. There should be at least two ways of getting around an obstacle, requiring different types of ability checks or skill checks to overcome the obstacle's DC.
Lead Runner. This is what everyone is chasing. He should be assigned a lead runner DC, higher than most obstacle DCs, to represent how competent he is at evading capture.
How to run a chase:
Each character that gives chase rolls initiative, and is given an equal rank behind the lead runner. Characters encounter obstacles and roll ability checks against the obstacle's DC. Characters fall behind and lose a rank if they fail to beat the obstacle's DC, they maintain their rank if they beat the obstacle DC, and they catch up and gain a rank if they also beat the lead runner DC. Characters that are considerably faster, through mundane or magical means, can gain two ranks if they beat the lead runner DC. At the beginning of every turn, those with the lowest ranks (those in the front of the chase) move to the beginning of the initiative order. If a player reaches rank 0 (tied with the lead runner) they can attempt to catch the lead runner and end the race. If combat ensues, the characters arrive according to their rank, being delayed by that many rounds before they arrive.
Keep the momentum going; call for checks quickly and describe things in a hurry. The players should feel like they're rushed, just like their characters. You can track initiative (and by extension, rank) on a sheet of paper, but it's much more fun to use miniatures or initiative cards to act as an easy, visual reference for where everyone is in the chase.
Lastly, have a plan for what happens if the runner is caught, and plan for if he isn't. For some of you, this might seem like no-brainer advice, but it's easy to fall into the trap of prescribing events, removing your layers' choice because you have an idea of how you would like the chase to resolve. Have a plan for both, and roll with the punches.
A Practical Example: The Lightning Train
For those of you reading after the release of the Introduction to Manifest Campaign Setting, this practical example is not set in my primary campaign world of Manifest, but instead in a very different magitech world.
There's a bomber aboard the lightning train. If he completes his spell, he'll set of a series of rune bombs (of the type the party encountered recently), utterly destroying the train and killing everyone onboard. Thankfully, Bumble the Beeforged and Will the Artificer spot him attempting to sabotage the engine at the front of the train. He sprints past, and they give chase.
The bomber ducks into the cargo car, leaping over crates and packages, sending them tumbling down. Bumble and Will make Dexterity checks to leap after him. Gracefully, Will follows along, while Bumble (true to his name) trips on a handbag. The bomber scurries up a ladder to the top of the train, Will close behind.
Bumble opts for a different strategy: making repeated Strength checks he tackles his way through the lower level of the train, tossing aside carts, passengers, and doors with force, keeping pace with the fleeing bomber. Meanwhile, Will and the bomber make Dexterity checks to maintain their balance in their chase atop the train. Will's footing begins to slip, and the bomber pulls further ahead, leaping to the final car, an open cargo car.
Bumble throws open the door to the final car to meet a shower of sparks; the bomber has plunged his weapon into the latch adjoining the cars. Just then, Will leaps over the gap, landing on the final car behind the bomber. The cars begin to slide apart, the final car disconnecting from the train. Bumble makes a last-ditch effort, a Dexterity saving throw to leap aboard the ever-widening gap. He succeeds, and the two tackle the bomber, ending the chase.
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