Chases in d20
This is system that is intended to represent fairly cinematic chase scenes without the need for new skills feats, and to do so in an abstract way. They’re designed for foot chases, but can be used for any sort of chase with a little adjustment.
Lead – the distance between quarry and pursuit. Each round the Quarry adds to it, and the pursuit subtracts from it.
In most cases, the Quarry will have an initiative advantage over the Pursuit -- the quarry will have started to run and the pursuit followed.
One conceit we will allow ourselves for the sake of clarity is related to that. During a chase no matter how big the lead is, the pursuit will react to the moves made by the quarry on the pursuit's next action.
Terrain:
Clear - Wide open ground that offers no cover, obstacles, etc. Escape is very difficult here if you cannot significantly outrun you pursuit.
Open - Space that is mostly unobstructed, that is open enough to run, but that provides some small opportunity for cover, obstacles, etc.
Close – Space is too confined for a full run – the top speed is a double move. There’s a lot of room to hide and plenty of obstacles, but it’s much slower going.
Tight – Space is so confined that all movement rates are halved, and no one may run. This involves a lot of climbing and crawling over things – obstacles almost every round, etc.
In a given chase round, Action moves like this:
1. DM Determines DM Obstacle, if any
2. Quarry moves, selects and resolves actions
3. Pursuit moves, selects and resolves actions.
1. DM Determines Dm Obstacle.
Based on the terrain type, there is a chance that there is a randomly determined obstacle in the path of the chase. The skill needed to clear the obstacle – and the DC – are randomly determined. It’s possible to use one of the other skills listed to clear the obstacle, but at a +2 improvisation penalty (for deciding to tumble over a hurdle rather than jump it, etc).
If there is an obstacle, running is impossible.
Obstacle Chance:
Clear – 0
Open – 1 in 6
Close – 1 in 4
Tight – 1 in 2
Skills:
Balance
Climb
Jump
(Tumble)
DC: 10 + 1d10
2. Quarry Action
If there was a DM obstacle, clearing the DM obstacle is a Move Equivalent Action. Before or after the Quarry can take a standard action.
Run (Clear & Open Only) remember the rules for exhaustion – run for a number of rounds equal to con before starting to make saves, etc.
Push It (Clear, Open & Close Only) (Variation on Run or regular move - Con test DC 15 – success indicates pushing for an extra 5 feet this round, +5 feet for ever 5 over 15 the test result was (+10 at 20, +15 at 25). Fail by more than 5 and the runner must make a reflex save of DC 20 to avoid falling down. Pushing it adds 1 to the “cost” of the round in endurance – pushing it while running counts as two rounds of running, not one. Pushing it while taking normal movement counts as a round of running.
Double Move (Any) Remember that in Tight terrain the movement rate is halved.
Create Obstacle (Open, Close, Tight) – Quarry spends a standard action to try to create an obstacle that the Pursuit will have to clear. Makes a dex or str check (quarry’s choice – or something else, if that seems appropriate). The result is the DC of the obstacle created. –4 Penalty to Create Obstacle tests made in Open terrain.
Bluff & Hide (Open, Close, Tight) – 4 penalty to Bluff & Hide tests made in Open terrain. +4 Bonus in Tight terrain. Quarry makes an opposed Bluff (Sense motive) test to distract the Pursuit. If that succeeds, she may make and opposed Hide (Spot) test to try to hide from the Pursuit.
Lay of the Land. (Open, Close, Tight) Make an opposed Knowledge(area) test to use the quarry’s knowledge of the area to build her lead. Winner of the test gains 5’, +5’/5points by which she won the test.
Change Terrain (Free Action) Try to find a new terrain type to enter. The Quarry declares what terrain type she would like to find. Moving into a new terrain type may take a few rounds, depending upon the terrain the chase is in:
Clear 1d6 rounds
Open 1d4 rounds
Close 1d3 rounds
Tight 1d2 rounds
Note: The change does not happen until the beginning of the appropriate turn, and may be contested by the Pursuit.
Spot (Movement Action) Try to see the pursuit, if the pursuit is hiding successfully
This change is at the DM’s discretion, depending upon the setting. The Quarry can change her mind each round, looking for a different sort of terrain.
3. Pursuit Action
If there is either a DM obstacle, or a Quarry obstacle, the Pursuit must spend a movement action navigating the action, as above.
Beyond that, the Pursuit can take the following actions:
Run (Clear & Open Only)
Push It (Clear, Open & Close Only) (Variation on Run or regular move - Con test DC 15 – success indicates pushing for an extra 5 feet this round, +5 feet for ever 5 over 15 the test result was (+10 at 20, +15 at 25). Fail by more than 5 and the runner must make a reflex save of DC 20 to avoid falling down. Pushing it adds 1 to the “cost” of the round in endurance – pushing it while running counts as two rounds of running, not one. Pushing it while taking normal movement counts as a round of running.
Double Move (Any) remember that in Tight terrain the movement rate is halved.
*Create Obstacle (Open, Close, Tight) – Quarry spends a standard action to try to create an obstacle that the Pursuit will have to clear. Makes a dex or str check (quarry’s choice – or something else, if that seems appropriate). The result is the DC of the obstacle created. –4 Penalty to Create Obstacle tests made in Open terrain. For the Pursuit, there needs to be a plausible way for the pursuit to create an obstacle ahead of the quarry for this action to be possible.
Bluff & Hide (Open, Close, Tight) – 4 penalty to Bluff & Hide tests made in Open terrain. +4 Bonus in Tight terrain. Quarry makes an opposed Bluff (Sense motive) test to distract the Pursuit. If that succeeds, she may make and opposed Hide (Spot) test to try to hide from the Pursuit. If the Pursuit succeeds in both bluff and hide tests, the Quarry will not know if the Pursuit has been lost, or how close the pursuit is.
Lay of the Land. (Open, Close, Tight) Make an opposed Knowledge(area) test to use the quarry’s knowledge of the area to build her lead. Winner of the test gains 5’, +5’/5points by which she won the test.
Contest Terrain (Movement Action) The Pursuit may wish to try to prevent the quarry from entering a certain type of terrain. The Pursuit makes a knowledge(area) or Dex test, opposed by the quarry’s Knowledge (area) or Dex test. If the Pursuit succeeds, the Quarry cannot enter the new terrain. This is only possible when the lead for the chase turn is less than 10.
Attacking in a Chase.
This isn’t easy.
Ranged Attacks:
The easiest attacks to make are ranged attacks. Either Quarry or Pursuit spends a standard action, as normal, making an attack rather than moving.
There may be cover or concealment for the target, depending upon the terrain:
Clear – None
Open – 25% concealment for every 50’ of lead.
Close – 25% concealment for every 20’ of lead
Tight – 25% cover for every 10’ of lead.
Melee attacks –While Running
At a dead run, it is next to impossible to make a melee attack. If something, like an obstacle, should slow up one of the participants, the other might be able catch up enough to make an attack.
The only melee action possible, given that the pursuit can close to within 5 feet of the quarry at a run, is a trip attack (mean to represent a variety of tactics for bringing the quarry down.
Since a charge allows a character to move an amount equal to twice his or her movement, it amounts to the same amount of movement as a double move, so in close or tight quarters it’s possible for a character who is right on the heals of his quarry to make an attack. The quarry will have to choose between turning and fighting or running, and hoping to make her way to open ground to try to avoid those attacks – or to put some obstacles between her and the pursuit.
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