Cortex Prime Car Chases

Again with the car chases. After several attempts across multiple ad-hoc systems, I think I’ve twisted the excellent ttrpg toolkit Cortex Prime into something that’ll run satisfying car chases.

Setup

My take on the car chase is a modified contest*, to use Cortex terms. You have a runner who is trying to escape from a hunter. Dice pools for the chase are built from prime sets across the drivers and their vehicles:

1. Vehicles have Speed, Handling, and Body attributes.
2. The drivers have a Vehicles skill.
3. As always, the third die comes from a Distinction.

*You can do a decent chase with the default contest rules in Cortex. These rules here just arrange things so there’s some environmental dangers and some interplay between vehicle traits and the fiction.

Overview

1. The runner and hunter have a contest.
2. The loser of the contest takes stress to the vehicle trait they rolled and might get taken out.
3. The GM may spend Chase Pool dice to attack both drivers.
4. If the loser is willing and able to continue, they initiate a new contest. Go to step 1.

The Chase Pool

The thing about street fights… the street always wins.

Dom Toretto, Furious 7

The Chase Pool represents obstacles and dangers during the chase. When a driver rolls a hitch, that driver gets a PP and the GM may either 1) add a new die to the Chase Pool equal to the one that rolled a hitch or 2) step up an existing Chase Pool die.

You can use 2d6 for the Chase Pool starting value, like a Doom Pool. For a slower burn, you can start with nothing in the Chase Pool and only use dice from hitches to build it out. For a more perilous chase, start with the Speed die from each driver and maybe throw in a third die based on traffic congestion or how tight and twisting the terrain is.

Between contests the GM may spend dice out of the Chase Pool and roll an attack on both drivers. Dice spent in this way are spent permanently. The Chase Pool generates a total and each driver must roll to beat that difficulty or take stress to the vehicle trait they chose for the test. If the Chase Pool rolls hitches, either driver may spend PP to step down their vehicle stress.

Stress vs. Complications

No, Cortex Prime doesn’t seem to address stepping down stress during a conflict, but you can step down complications when the GM rolls hitches and I think that translates just fine. I use “stress” here because it’s tied to the three vehicle traits but in the fiction stress from chases could be ephemeral as easily as it could represent actual damage.

1. Speed stress involves gaining or losing ground, being overtaken or outdistanced. Actual damage represents power loss – engine or transmission damage, blown radiators, and so on.
2. Handling stress represents loss of control. Fishtailing, spinning out, throwing your car around recklessly. Actual handling damage is easy to come by, however – blown tires, alignment damage, broken axles, and brake damage.
3. Body stress maps most easily to physical damage. Spiderwebbed windshields and crushed fenders, ripped-off doors and twisted metal. You may rule that drivers may not spend PP to step down Body stress when the Chase Pool rolls hitches.

I prefer the Shaken & Stricken mod for vehicle stress. The line between stressed and shaken can be where stress tips over into actual damage – broken driveshafts and wheels coming off. Plus, being taken out when two traits are shaken instead of requiring stress to get raised above d12 means you’ve got a little more variety in bringing chases to an end.

I also would use the following mods:

1. Drivers may push their stress, adding it to their own pool for a roll, after which it’s stepped up. Perhaps the hunter has almost lost sight of the runner, but uses their high Speed stress to their advantage. They are able to see the path their quarry takes and have ample time to find a shortcut or react to danger.
2. Usually the contest initiator chooses what vehicle trait applies to the contest. If the runner chooses Speed, the hunter must counter with Speed. A driver can spend a PP to roll a different trait, using their Handling to swerve out of the way of a hunter’s ramming attempt, for example.

Why This Works For Me

1. The choice of what trait to include should tie into the story. Using Handling to whip through side alleys should be different than choosing Body to smash through fences and into your opponent’s car.
2. There’s a simple relationship between stress, hitches, success, and failure. Roll a hitch? The Chase Pool grows. The GM doesn’t have to think about whether to saddle you with a complication. Fail a contest? You take stress to the vehicle trait you rolled (this is a shift from Cortex RAW, which states the victor chooses the type of stress).
3. The environment matters. The Chase Pool is a common enemy but isn’t a frequent threat, keeping the focus on the chase participants.
4. Vehicles matter. Being able to easily build a dice pool in Cortex from any combination of prime sets is one of the system’s greatest advantages.

An Example Chase

The freeway is a dangerous place to have a car chase. The Chase Pool starts at 3d8 – 1d8 for each driver’s Speed die and an additional d8 for the traffic.

Runner Quarry Jr. sees the police car in his rearview and takes off down the freeway, passing commuter cars. He rolls Speed d8+Vehicles d8+Career Criminal d8 and gets 3+6+8 for a 14. Officer Hunter grits her teeth and rolls Speed+Vehicles+Corrupt Cop to keep up. She gets a 1+7+8 and beats Runner with a 15! Her hitch goes into the Chase Pool, though (granting her a PP), which steps up a die resulting in a Chase Pool of 2d8+1d10. Runner spends his single PP to add the 3 into his result for a 17. Hunter goes for it – she gets 6+4+1, for a 10. She should’ve stayed. The GM decides to add that d8 to the Chase Pool, for 3d8+1d10. At least Hunter has 3PP now. 17 vs. 10 is a heroic success in Runner Quarry Jr’s favor, but he had to use his PP to add all his dice to do it. His effect die steps up from d4 to d6 and gets applied to Officer Hunter’s Speed as stress.

The GM decides the Chase Pool is gonna kill everyone and rolls all the dice – 3d8 (5,8,4) and 1d10 (8). The freeway traffic tangles in front of the drivers. This GM is sadistic and adds the 8 and 5 for a 13, choosing a lower total so the effect die can be a d10.

Runner uses his Speed to try to get out in front of the congestion. He rolls 3d8 and gets 1+2+4. His 6 is nowhere near the Chase Pool’s 13. He takes d12 Speed stress (d10 effect die stepped up for the freeway’s heroic success), slamming on the brakes. Something blows under the hood and Runner’s car starts smoking. He gets a PP from that hitch, which sets the Chase Pool back to 1d8, but at what cost? His Speed is shaken – if he’s forced to roll Speed again he’ll only keep one die for his total.

Officer Hunter uses her Handling to snake through traffic. She gets 2+3+6, and her 9 isn’t enough to prevent her from taking d10 Handling stress. She scrapes a minivan on her way through the snarl, and now she’s pulling to the right.

At the end of the first contest, this is how everyone stands:

Chase Pool: 1d8

Officer Hunter lost the contest. She’s not letting Runner go, and she’s not taken out, so the corrupt cop initiates a new contest. She puts the hammer down, choosing to roll Speed+Vehicles+Corrupt Cop. She spends 1PP to push her d6 stress, adding it to her own pool. She knows Runner can’t do the same, or else he’ll take himself out. Hunter roll 3d8 (3,8,8), 1d6 (2), and 1d12 for Runner’s Speed stress (1). Hunter was hoping the d12 would at least be an effect die, but the hitch takes it out of her pool completely and adds it to the Chase Pool (1d8+1d12). Still, her impressive 16 is consolation enough.

Runner Quarry Jr. doesn’t like the look of this. He’s in a rules example, though, so he goes for it. His Speed d8+Vehicles d8+Career Criminal d8 betray him and roll 1, 1, and 3. The Chase Pool adds two d8s (3d8+1d12), but that doesn’t really matter: Runner’s 3 is more than 10 less than Hunter’s 16. Any stress is enough to step up his d12 Speed stress and take him out, but he really stunk this one up. Officer Hunter forces Runner Quarry Jr. off the road where he bottoms out and snaps his driveshaft.

The chase is over.