From: hall@bcstec.ca.boeing.com (Robert J. Hall)
Subject: net.rpg - damage system
Organization: Boeing
Date: Wed, 16 Dec 1992 16:47:26 GMT

I attempted to clean up the damage system notes I posted earlier so it
would be cleaner and more understandable. More additions also included.
Hope you like it...

NET.RPG - PROPOSED PHYSICAL DAMAGE SYSTEM

  This system deals with the damage caused by a solid physical object strik-
  ing a location on a body with a given velocity, angle of attack, shape,
  and mass. It does not yet deal with other forms of attack, such as
  explosions, acid, fire, electric shock, freezing, and so on, although it
  may be possible to integrate such effects into this system.

  The system is only intended to be an approximation of the actual physics
  involved. No damage system can ever be completely accurate, and certain
  simplifications were necessary to make it playable.

SCALE

  Some of the numbers used in this damage system will be based on an expo-
  nential scale. This means that for each increase in a value, the actual
  quantity the value represents will be increased by a multiple. The
  standard increment will be based on the size of the dice being used. For
  simplicity, the actual quantity will be doubled for each dice worth of
  increase to the total. For example, if a ten-sided dice is being used,
  then each increase of ten is equivalent to a doubling of the factor being
  represented.

  Such exponential values, of necessity, must be based on a specific dice
  size. A common dice size, such as 6 or 10-sided, will need to be selected
  before any solid tables of weapon, armor, or creature data can be con-
  structed. However, a conversion table can easily be included in the
  appendix for different dice sizes.

  The actual values will be in metric. Lengths are in meters, mass is in
  kilograms, force is in newtons, and energy is in joules.

WEAPON TYPES

  There are three standard categories of physical weapons, based on the
  shape of the striking surface.

  POINT - These weapons have a tapered tip that comes to a sharp point. The
  tip is used to breach the surface, while the tapered sides widens the
  wound as the tip travels deeper into the body.

  WEDGE - The edge of this weapon is a straight or curved line. The edge
  makes the initial penetration into the body, then the widening sides open
  the wound while the blade slices deeper into the body. Some compression
  will occur along the axis of the edge.

  HEAD - The tip of this weapon is a wide flat or curved surface. The impact
  will compress the surface under the head, sending shock waves radiating
  from the area of contact.

  Some weapons can include a combination of these different striking surfaces.

STOP FACTOR

  In this damage system, some amount of the weapons kinetic energy is
  expended to penetrate the external defenses of the target. The difficulty
  of this penetration is given by an equivalent cross-sectional area. This
  area is used to determine the stop rating of the weapon. The greater the
  area, the larger the stop rating.

  For a flat-headed weapon, the penetration area will be determined by the
  total area of impact. Blades and points will be based on a cross-section
  at some distance up the cutting edge. Sharper blade or point weapons will
  have a smaller area and a lower stop factor.

  The stop factor is an exponential rating. For each dice increment in the
  stop factor, the equivalent penetration area is doubled. Since the area
  increases as the product of two dimensions, doubling the size of a weapon
  will increase the stop factor by a total of the two base dice.

DAMAGE COMPLEXITY

  Damage due to weapons penetration is systems-based, meaning that the
  weapon causes damage to specific systems within the body. To allow for a
  range of complexities, the systems are organized in an outline format,
  with each subset describing the systems in finer and finer detail.
  Obviously there is a certain amount of overlap in system functions. Such
  overlap will be factored in during the damage procedure.

  The amount of complexity required by the GM will determine the level of
  system detail required:

  Level 1 - Exterior/Interior

    The simplest damage level determines whether or not the weapon inflicted
    damage to the exterior or the interior of the body. The exterior
    includes all body systems that interact directly with the external
    environment. The interior includes the remaining systems that support
    the bodily functions, but only interact indirectly with the outside
    environment.

  Level 2 - System Groups

    These are groups of organs that work together to support a specific
    function. External systems include weapons, locomotion, senses, and
    protection. Internal systems include power, energy, and control.

  Level 3 - Individual Systems

    These are specific organs or groups of tissue that perform a dedicated
    task. Such systems include the heart, lungs, brain, stomach, hand, eyes,
    ears, shoulders, and so on.

  Level 4 - System Components

    These are the bits and pieces that go together to make up an individual
    system. Components include thumb, cornea, heart value, etc. This level
    of detail is probably unnecessary for most purposes.

  Shown below is a Level 2 systems outline for a human:

  External       Primary Combat Function            Sample level 3 systems
  -------------  ---------------------------------  ------------------------
  Protection     Protects the body from damage      Skin, bones, tissue
  Mobility       Allows the body to move rapidly    Legs, feet
  Weapons        Make attacks or ward blows         Arms, hands, and teeth
  Sensors        Observe opponents and obsticles    Eyes, ears, nose
  Miscellaneous  Distraction                        Hair, sexual organs

  Internal       Primary Combat Function            Sample level 3 systems
  -------------  ---------------------------------  ------------------------
  Power          Maintain activity level            Heart, lungs, arteries
  Energy         Recover from fatigue               Stomach, intestines
  Command        Control the other systems          Brain, spinal cord
  Miscellaneous  Special                            Glands


WEAPON DAMAGE

  The kinetic energy of the weapon is determined by the success of the
  attack and the attributes of the attacker. An inept or partially blocked
  attack will have a lower energy than normal. Likewise, a weak or fatigued
  attacker will be unable to propel the weapon as rapidly.

  The weapon will strike at a specific location on the body. If the location
  is an external system, then the kinetic energy of the weapon will be
  expended in the form of damage to the selected system. When a strike is
  made at an internal system, part of the energy is expended to penetrate
  the external protection system.

  Each internal system will include an external protection rating which
  determines how many damage points must be spent in penetration. The weapon
  stop factor will determine how many additional damage points are spent as
  concussion energy against the external protection. The remaining amount is
  the number of damage points inflicted on the internal system.

  The Damage point total is an exponential rating. For each dice increment
  in the Damage points, the equivalent kinetic energy is doubled. Each dice
  worth of Damage points absorbed by a system will half the Kinetic Energy
  of the weapon.

SYSTEMS TABLE

  There are two methods to determine the system struck by the weapon. Either
  a random table is used to pick the system, or a system is targetted by the
  attacker. In the latter case, the attack receives a negative attack
  modifier due to the difficulty of hitting a specific target. If the
  targeted system is missed, there is still a chance the blow will strike
  another random system. The odds of such a hit, however, are lower than
  normal. (See combat rules for further details.)

  Each creature or character will have a systems table which will display
  various combat factors for each system. A sample table is shown below:

      %    Target  External System  Serious  Critical  Armor
    -----  ------  ---------------  -------  --------  -----
    01-30    -1    Protection         10        20
    31-40    -3    Mobility            6        12
    41-50    -3    Weapons             5         8
    51-55    -6    Senses              1         2
    56-60    -5    Miscellaneous       3        10

      %    Target  Internal System  Serious  Critical  Prot.  Armor
    -----  ------  ---------------  -------  --------  -----  -----
    60-65    -4    Power               1         2       4
    66-85    -2    Energy              2         4       2
    86-90    -3    Command             1         2       3
    91-00    -2    Miscellaneous       2         5       2

  The first column is a percentile table that is used to select a system at
  random. Of course, some other dice can be used, as long as the values are
  roughly proportional. The second column is the modifier to the skill level
  when the attacker targets that specific system. The third column is the
  name of the system. The fourth column is the number of damage points
  needed to inflict a serious wound to the system. The fifth column is the
  number of damage points needed to inflict a critical wound. The sixth
  column of the internal damage table is the external protection level for
  the specific system.

  (Table values are the weighted averages of the values from the more
  detailed wounds level. Thus, each value for External is the weighted
  average of the corresponding values for Protection, Mobility, Weapons,
  Senses, and external Miscellaneous. For the weights, use the ranges in
  the percentile column.)

ARMOR

  When external armor is worn, each system receives an Armor rating that is
  entered in the systems table. The rating is the number of damage points
  absorbed by the armor prior to any wound determination.

  Each piece of armor provides different numbers of Armor points to
  different systems. A Helm, for example, could provide 20 points to
  Command; 15 to Senses; 5 to external Miscellaneous; and 5 to Protection. A
  separate table is used to record each piece of armor worn, and the number
  of points provided to each system. The Armor points are totalled for each
  system, and the results are then entered under the Armor columns in the
  appropriate rows of the systems table.

  Armor that is designed to cushion an impact will have higher ratings for
  the External systems. Likewise, armor designed to prevent penetration will
  have higher ratings for the Internal systems. (Possibly each piece of
  armor could include a damage overload factor - the level of damage points
  needed to break the armor. Not sure how to include this, however.)

  For the sake of simplicity, complete suits of armor will be described
  using the total Armor points in each system. (This is instead of a
  complete listing of the armor components and the points each provides to
  the various systems.) A complete equipment list will, however, still
  describe individual pieces of armor.

WOUNDS

  There are three wound categories:

  MINOR - Easily repaired wounds that have a minimal impact on the body
    performance. Many such wounds will increase fatigue and impact the
    overall health.

  SERIOUS - A wound that is detremental to the performance of a system. The
    system will continue to operate at a lower level of efficiency. The
    effect on the creature or character will depend on the specific system
    impacted. The effects of a loss of system effectiveness would be as
    follows:

      Protection     Reduced ability to absorb internal damage
      Mobility       Loss of speed and agility
      Weapons        Decrease in combat weapon/shield skills
      Senses         Temporary loss of sight, hearing, etc.
      Power          Reduction in actions per round
      Energy         Unable to recover strength
      Command        Stunned, dizzy, paralysis, and/or unconsciousness
      Miscellaneous  Special effects.

  CRITICAL - A very nasty wound that seriously disrupts the target system.
    The special effect will be determined by a critical wounds table for the
    system. (Separate critical wound tables will be needed for each level of
    complexity.)

  When damage is applied to an internal system, the damage to external
  protection is always computed first to determine if any Critical wounds
  occur. Such critical wounds can impact the resulting amount of damage to
  the internal system. For example, suppose the blow is to the Power system.
  If the external damage is sufficient to cause a critical wound, then
  damage beyond the critical level is also applied to the Power system. This
  could be interpreted as smashed bones that no longer protect the Power
  system - resulting (for example) in a crushed rib cage and collapsed lung.

IN GAME TERMS

  As a minimum, all creatures include a Level 1 systems table describing the
  External and Internal systems. Where further detail is required, the
  wounds table can be expanded to higher levels of complexity. Each level of
  table should be kept separate for easy access, and the values for each
  wound system should be the weighted average of the values from the more
  detailed wounds system. For character races, the wounds table should be
  developed to at least level 3, with level 1 and 2 tables included as well.
  At level 3 or above, additional details can be included for the various
  body systems - especially for critical wounds.

OTHER ADDITIONS?

  - Wounds that overlap multiple systems. (Big weapons with lots of energy)

  - Weapon penetrates all the way through the body. (Only part of the
    kinetic energy causes damage)

  - Variable systems complexity. (More detail for key systems, such as
    Heart, Brain, Hands, etc.)

  - Damage from other sources. (Fire, cold, electricity, acid, etc.)


-- 
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 Boeing Computer Services   |      mv message /compost/heap/$$
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