Post-Apocalyptic Chase Rules– Vehicle and Foot Combined

These chase rules are meant to be used with these post-apocalyptic vehicle rules, although they could be adapted to other vehicle rules pretty easily.

They're also meant to be used for foot chases, so they can be used to create awesome parkour chase scenes.

Moreover, they can be used for combined vehicle and foot chases, like if someone on foot is being chased by someone in a car.  Obviously there's an issue there in that vehicles are just plain faster than runners– I'll explain how to deal with that later.

This is very loosely inspired by Spellbound Kingdoms, much like my system for using character bio as skills.

Rolling Initiative

Initiative is side initiative for people on foot, and by vehicle for people in vehicles.

Roll d20 (or 2d10 or whatever your chore mechanic is) plus DEX mod plus maybe a relevant driving mod for each driver.  That is their vehicle's initiative, and everyone in the vehicle goes on that initiative score, including not only passengers but also prisoners or boarders from the other side.

For each side, do the same thing but have whichever character is the most dextrous, best at parkour or whatever, roll for their whole side.  If there's a skill system they can add their athletics skill or whatever is most likely to get used, the same way drivers can add their driving skill.

Break ties by who has the highest skill, highest modifier, or just by rolling dice.

Chase Positions and Range Bands

At the the start of the chase, figure out who is in the lead, who's being chased by everyone else– they're at range zero.  Anyone within like 30 feet or less, or the range of a taser or thrown rock or dagger, is also at range zero.

Anyone within a hundred feet or so, or easy pistol range, is at range one– they're one range band behind the lead.

Anyone within around 500 feet, so fairly easy rifle range or extreme pistol range, is at range two.

Anyone within less than a couple thousand feet, so sniper rifle, heavy machine gun or anti-tank rocket range or extreme rifle range, is at range three.

Anyone within about a mile, or extreme range for sniper rifles and heavy weapons, is at range four.

Anyone within about 3 miles is at range five.  At this range you're still visible assuming no obstructions, but you're out of range of any weapon short of tank cannons or guided missiles.

Anyone at 3-9 miles away is at range six.   At this range you might not be visible even with few or no obstructions, you might be over the horizon, but anyone chasing you has at least a rough idea of where you are.  Also you might be leaving a visible dust cloud even if not visible yourself.  People at this range can keep chasing you but at the referee's discretion might have to make a tracking test or something to make sure they go the right way.

Anyone more than ten miles away is at range seven– they've lost track of the person in the lead.   If someone else is at range six, maybe they could follow that person and hope for the best.

I wrote those ranges mainly with post-apocalyptic car chases in mind; for pure foot chases in a crowded urban environment, keep the same system but maybe re-interpret the range bands as being shorter.

Obviously the logarithmic scaling of these range bands means time is somewhat abstracted; a combat round in a chase represents a rather indeterminate, abstracted amount of time.  If that becomes an issue for spell durations or bard car songs or something, treat each round as being ten seconds if people are at close range, and a minute if the closest chases is out of weapons range.  Or something like that.

Actions During Combat

On their initiative each round, each character takes a movement action, and might also take a non-movement action.  Note that if you're driving or on foot, you have to take a movement action.  Even staying still is an "action" in the sense that it causes you to fall behind and affects your position relative to everyone else.  Only passengers get to not take movement actions.  

Here are the options people have– or at least the ones that need to be codified for this system.

Chase Actions

I'll explain DC's for chase and other movement actions at the end of this section.  

Chase actions can cause you to gain or lose a range band.  If you're not at position zero, this means you get closer or further to position zero.  If you are at position zero and you can a range band, you stay at position zero and everyone else falls a range behind.  If you're at position zero and you fall back a range, you fall to position one if someone else was at position zero with you, or everyone else gains a range if nobody else was at range zero.  

Note that things like ramming and other maneuvers are not considered chase actions, since they don't change your chase position.  

Hold Pace– This is the equivalent of running but not sprinting, or driving fast but not pedal to the floor.  If you do this, you can also take a non-chase action, but it's at disadvantage unless it's something that directly involves movement like ramming, maneuvering, etc.  

Make a driving or athletics check.  On a success you stay in your current range band, on a critical success you either move up a range, or can give one passenger advantage on a non-movement action this round, or ignore your own disadvantage, your choice.  On a failure you fall back one range, on a critical failure, save or crash. 

Push It– Sprint or put the pedal to the metal to try and gain range.  Make a driving or athletics test.  On a success you gain a range band, on a critical success you can gain two if you want.  On a failure you simply don't gain a range band, on a critical failure, save or crash.  

You can't take any non-chase actions if you pick this, other than ramming, dive tackling someone, etc.  

Slow Down or Stop– You deliberately fall back.  This doesn't usually require a test at all, but it might if you're in a vehicle, want to stop altogether and were pushing it last round, or if the terrain makes it especially difficult, like you're on ice.  

You can take a non-chase action without disadvantage this turn.

DC's for Chase Actions and Movement Actions

For any chase action or any non-chase action involving movement like ramming, the DC is determined by terrain.  Drivers will make tests using either their vehicle's speed or handling modifier.  

Runners will usually use dexterity, but very occasionally might use strength.

Encumbered runners, or heavily encumbered runners (whatever the equivalent of having a heavy backpack that would significantly slow you down is called in your system) get disadvantage on all chase actions and other movement actions. Being encumbered in a chase is really, really bad.

Runners from a race that has a lower movement speed, like dwarves, get disadvantage on tests related to raw speed, but not tests relating to agility.  If you have higher than normal speed, you get advantage instead.  

For mostly open terrain, the DC is 10 for speed and you can't rely on handling/agility.

For somewhat cluttered terrain, it's 15 either way.

For very dense terrain, it's 10 for handling/agility and you can't make speed tests; you have to use agility.  

If it seems weird that dense terrain actually makes handling tests easier, remember that what's being measured is not your absolute speed, but your speed relative to everyone else.  

If you're in the lead, you're free to choose which way you want to go, and the people chasing you largely have to follow you.  If you're following, you need to either follow the path of whoever you're chasing, find a shortcut, or potentially take a long way around to cut them off if you're in a car and they're on foot.

Finally, a word about speed differences.  Cars with high speed are faster than cars with low speed, and high-dex people are faster than low-dex people.  Not by enough to automatically outrun each other though; just, they are likely to win contests, but they still have to roll.

Cars vs people, or planes vs cars for that matter, are a different story.  Cars automatically succeed on speed tests vs people, and people automatically fail them vs cars, ditto for cars vs most aircraft.  If you're on foot running from a vehicle, you pretty much have no choice but to go into dense terrain where the chase actions will have to be handling/agility based; you can't win on raw speed.   

Non-Chase Actions

Attack– This works pretty much as normal, with two considerations.  First, you may get disadvantage on an attack if you're at long range, or if the target is moving across your field of vision, fishtailing wildly, etc.  Second, people in cars are likely to get some kind of cover bonus to AC.  

Use an item, cast a spell, etc– Again, this works pretty much as normal.  People might need to make a DEX check to do it while running or in a bumpy car though.  

Full Defense– Usable by drivers or people on foot only, you take some evasive maneuvers.  Make a driving or athletics test; on a success, attacks against you have disadvantage until your next turn, but so do attacks by any of your passengers if you're driving.  Doesn't apply to attacks from the same range band, or to ramming attempts.  

Ram, or dive tackle someone– Make a driving, athletics or grappling test against the target's unarmored AC.  You have disadvantage if you weren't in their range band at the start of your turn, i.e. if you sped up to catch them then tried to ram.  However this doesn't stack with the disadvantage from your chase action, and you can try to do this even if you pushed it.   

A successful dive tackle during a chase does d4 damage on soft ground, or d6 on hard ground, and then you're on the ground grappling.  

A successful ram does damage to both vehicles.  Each vehicle inflicts one die per size, so one die for motorcycles, two for cars, three for large vans, etc.  The die size is d4 if the vehicle's velocities are nearly matched, like you side-swipe or bump someone front to back, and d6 if you come in more from the side.  If two vehicles collide head-on, they both inflict d8, and if you t-bone someone, you inflict d10's and they inflict d6's.

Armor modifies damage.  Reduce damage taken by one for every point of armor.  Increase damage inflicted by one for every two points of armor.  

It is imperative that you do armor this way, even if it otherwise acts as hit avoidance in your system.  Treating armor as hit avoidance would imply that, say, a motorcycle ramming a tank is unlikely to damage either the tank or itself.  

If a car rams a person, treat this as if the person was a size 1 vehicle.  Their armor counts as half– personal armor isn't as substantial as vehicle armor– and only hard armor, like metal not leather, adds to damage inflicted.

Jump onto a vehicle, off a vehicle, or from one vehicle to another– Oh hell yes, you can totally do this, provided you and the vehicle you want to jump to are in the same range band.  

The DC is 10 if the two vehicles are less than 5 feet apart, 5 if they're locked together somehow, 15 if they're 5-10 feet apart, and 20 if they're 10-20 feet apart.  Disadvantage if what you're jumping from and what you're jumping to haven't roughly matched their velocities, including if tiehr vehicle's driver is doing full defense.  

Vehicles are always moving of course, so base this on the most opportune moment you think someone would get within that particular round.  

If you succeed you make it on or off the target vehicle, and you now act on that vehicle's initiative count, or on your side's "on foot" initiative count if you jumped to the ground.  Anyone onboard an enemy-driven vehicle acts just before that vehicle's initiative count, so if you board an enemy vehicle you get the chance to stab someone before they react, unless someone uses a held action or something to hit you as you jump.  

If you critically succeed you land so softly people don't feel/hear you land on the vehicle, though they might still see you.  If you fail you fall, take damage, and lose your next turn; save for half damage and to not lose your next turn.  If you critically fail, you don't get to save.

Note that while this potentially allows someone to game the initiative system by jumping back and forth, they risk falling every time they do so.  If this isn't enough to discourage people from jumping around constantly, your NPC's aren't maneuvering enough.  

Any other action people can think of– Rule as necessary.  This includes stuff like combat maneuvers to push people out of a vehicle, or called shots to take out a car's tires.

Chase Procedure

The referee will need a notebook and pen or pencil, or maybe some post-it notes.  Each round the referee will tell people what the terrain is like where they're located, giving them an idea what their options are.  i.e. you can speed along the road or try to veer off into the field, you can run down the alley, try to jump a fence, or climb a fire escape, etc.  

The referee will need to keep track of what terrain people have moved through in past rounds, since anyone chasing them and following their route will have the same options.  In essence, the referee only has to come up with new terrain when the person in the lead advances.

If people start taking different routes but still chasing the same person, treat them as being laterally separated by one range band.  i.e. if Mad Max is being chased by two bandit cars, and one car stays on the road Max is on while the other cuts through a canyon, the two bandit cars are one range band apart left-right in addition to any front-back distance.  

If people start veering off in different directions, you've essentially got two or more separate chases at that point.

Chases are over when one side gives up, gets killed, or the range distance between the people running away and the people chasing is seven or more.  Or if the people running find some clever way to hide other than sheer distance.  If the people running stop running, then you're into a standard combat.