Chase Combat

The following rules are meant to be used in tandem with the Random Chase Generator.

Legs

The chase is broken down into legs. Each leg represents a subset of the chase similar to the frame shots in a movie: careening around a turn to barely miss a baby carriage, barreling over San Fransisco-esque hills and spending part of your time airborne, etc. Each leg has the possibility for a turn, a change in street type (one way, two way, etc.), a change in traffic levels, and an obstacle (like the aforementioned baby carriage). These factors all combine to determine the difficulty of each driver's turn, with repercussions should the Pilot check be failed.

In each leg the vehicles involved roll opposed vehicle tests to determine their respective ranges (see step 5). The ranges are:

Outrun (distance = current chase speed x3): The Trailing Vehicle is way behind and in danger of being lost. If on the next vehicle test the Lead Vehicle scores more hits than this vehicle, it is able to escape this vehicle for the remainder of the chase.

Disadvantaged (distance = current chase speed x1): The Trailing Vehicle is at a significant distance from the Lead Vehicle.

Even (distance = a car length or so): The Trailing Vehicle is very close to the Lead Vehicle. At this distance it is possible to attempt Rams and Cut Offs (per SR4A p170). At this range, it is also possible to have passengers attempt to jump onto the Lead Vehicle. Or throw explosives, or take Polaroids of the Lead Vehicle's cockpit while following them through a -4G inverted dive.

Advantaged (distance = a car length or so, or up to the current chase speed x1 at the discretion of the driver): All the advantages of being Even, but with an extra little buffer for vehicle tests. Also in an Advantaged position an Advantaged Trailing Vehicle can actually be ahead of the Lead Vehicle. A vehicle in this position receives a +2 dice pool modifier to any attempt to Cut Off the Lead Vehicle.

Chase Sequence

1. GM Sets the starting distances for each vehicle.

2. The prey sets the speed of the chase. They may change it each leg by +/- their fast acceleration. A vehicle may exceed it's Speed by up to 25% but doing so causes a -2 penalty for all vehicle tests.

If you're going ridiculously fast through an area that doesn't support it (driving 200mph through the shopping mall), the GM should impose additional penalties on all vehicle tests.

A predator that can't keep up with the chase speed (even pushing to 125% of its Speed) falls behind a number of meters equal to the difference between its Speed (or 125% of that) and the chase speed. Once it drops below Outrun (chase speed x3) range, the predator is assumed to have dropped out of the chase.

3. Legs are generated and navigated until the Prey escapes or the Predator catches them. If the Prey crashes at any point, the Predator automatically catches them. If the Predator crashes, the Prey escapes.

Any driver may choose to break off and not make the leg's Pilot roll. If the Prey breaks off, he is automatically caught. If the Predator breaks off, the Prey automatically escapes.

Leg Sequence

  1. Add a leg
  2. The GM can choose to redo the leg if it doesn't make sense.
  3. The Prey can choose to redo the leg by spending a point of Edge. Drivers on the Prey's side of the chase may spend as much of their Edge as they choose. Passengers may also spend Edge, but only one per combatant per chase.
  4. Prey changes speed up to +/- their Fast Acceleration.
  5. The Prey rolls a vehicle test, modified by speed, if above or below the vehicle's Speed. All trailing vehicles do the same. If the Trailing Vehicle does not achieve at least as many hits as the Lead Vehicle, it slips down one range increment for each hit it is deficient. A tie results in no change. Net hits by a Trailing Vehicle may be used to move a number of increments up or down the chart at the driver's discretion.

    A predator traveling less than its Speed receives a +2 modifier on the above test for each full (fast Acceleration rating) it is below its Speed rating. So a Sports Car with a Speed of 240 and a fast Acceleration rating of 60 receives a +2 bonus at 180, a +4 bonus at 120, and a +6 bonus at 60.
  6. A normal combat turn is done. At some point in the turn the Predator and Prey must each spend a Complex Action to make a vehicle test (Reaction + Vehicle Skill + Handling) against the leg's difficulty. This counts as the one action per turn that is required to keep a vehicle from going out of control. If for some reason the driver is unable to make the test, automatically apply the effects of a critical glitch and the vehicle spins out of control.

Notes on the Generator

The listed difficulties are based on the Scion game system. For Shadowrun subtract one from the listed difficulty and cap it at 6. If any vehicle fails, apply the results for the obstacle to that vehicle only. If a player glitches they have successfully bypassed the obstacle but triggered some sort of negative effect, usually their vehicle going out of control. If a player critically glitches, apply the listed botch results in addition to the failure results. Some failures (such as a botch causing the death of a pedestrian) may remove that obstacle. In that case, if it was the Prey who failed, the Predator's threshold will not include the obstacle.

In general, aerial units in a car chase do not have to make piloting rolls to keep up. The driver of a ground vehicle can attempt appropriate maneuvers to lose them such as ducking through a parking garage, doing a 180 in a tunnel, or ducking and weaving through back alleys in heavily sky-scrapered downtown streets. Performing a maneuver can be done once per turn and is a Complex Action. The Prey sets the difficulty for his maneuver and if successful the aerial Predator(s) must succeed on an Intuition + Perception (or Pilot + Sensor) test to maintain pursuit. If the prey fails then pursuit is not shaken. In either case though, if any ground vehicles remain in the chase and are in communication with aerial vehicles, the aerial predators will rejoin the chase at the end of the next leg.

Common Chase Combat Modifiers

Situation Modifier
Driving with AR +1 die
Driving through VR -1 Threshold
Out of Control -2 dice to all tests inside the vehicle
Missing a tire -2 dice per tire
Defending while in a vehicle Good Cover, -2 dodge
Attacking while in a vehicle -3 dice, -2 more from the cover

Collisions

The collision rules on the generator are designed for Scion, not Shadowrun. In Scion the size of the thing you hit determines how much damage you take, while in Shadowrun it all depends on your speed and your own vehicle's Body. Since a yacht ramming a water scooter shouldn't immediately sink (it takes at least 36 DV under SR rules), but a tugboat ramming a speedboat probably should, use the following rules for collisions.

1. Determine the damage value of the collision. The base damage is the effective mass of the target + 3, plus the speed divided by 25 and then halved. i.e. Mass + ((Speed / 25) * 2). Yeah, it looks odd. But the numbers come out ok, and it's really easy to calculate with this form.

Collision DV Calculator
Mass: Speed:
Collision DV:

2. Resist the damage. If the DV is equal to or lower than the vehicle's armor, no damage is dealt. Otherwise roll the vehicle's Body + Armor against the DV. For incredibly sturdy vehicles the core rulebook suggests not even bothering to roll if the vehicle can resist it through buying hits.

3. Determine damage to passengers. If the vehicle sustains any damage, the passengers must resist that same amount of damage with Body + half Impact armor (including any vehicle armor). Vehicle modifications like Passenger Protection and Rigger Coccoon apply to this damage resistance roll. Note that this only applies to those who have purposefully bypassed a vehicle's safety features. Usually this means they're not in their seat (perhaps they're hanging out a window to shoot).