Shields vs Blasters

IC Explanation of Military Technologies

Blasters are simple: speck of plasma just fused from hydrogen generating its own magnetic bottle (think ball lightning), linear accelerator, bang. Thermal energy from the bolt, a little bit more converted from kinetic energy (blaster bolts have to move *fast* to hit the target before they cool down), and plenty of exciting radiation and ionization and stuff.

Using fusion power directly, blasters have a much better energy/mass ratio than other kinds of weapons, and still run almost forever on a negligible amount of fuel.

Shields involve a lot more handwaving on the part of the designer. Feel free to count the baseless assertions and instances of obfuscating double talk, multiply by the atomic weight of unobtainium, and store the result in /dev/null.

Shields protect a surface, not a volume (no walls of force or anything like that) and by default reflect/reradiate all matter and energy impinging on them, but can be tuned to allow small amounts or certain kinds of mass/energy to pass. Additional cleverness allows temporary holes to be opened in a shield at need.

The one thing a shield will never exclude is another shielded object: if two shields touch, they instantly combine into one.

Too much energy impinging on a shield will cause it to transmit some to the theoretically-protected interior; even more will cause it to collapse, burning out the generator (although it will still reradiate as much as it can). Shields that are expected to be exposed to modern weapon fire are constructed so that failure only blows up certain sacrificial components, which can be quickly replaced.

A shield's capacity is limited by how flexible it has to be, and also by how pure, seamless, and conductive the substrate is, in addition to generator power. Personal shields over skin or clothes are therefore weakest, with vacc suits, rigid armor, and vehicular hullfields being successively strong.

A shield covering a person will, in addition to keeping her safe from stubbed toes, bad vegetable-chopping technique, and lead pipes, keep her dry in the rain, clean in the mud, and warm in the snow. (A personal shield is somewhat thermally insulative, but cannot provide active cooling.) The shield usually follows the surface of the skin, but can include form-fitting clothing or small amounts of bulkier stuff such as belts or jewelry. It will not normally cover hand-held objects like swords; those require their own shield generators.

A personal shield generator masses about a kilo and is the size of a paperback book, but need not be in a single unit. Shield generators are often made as a heavy belt, but boots, bracelets, pectorals, and lumps in pockets are also popular. Like all modern equipment, shield generators are powered by fusion cells that last for years of usage.

Coincidentally, the energies at which an ordinary personal shield stops protecting completely are about those of ordinary blasters. Depending on the details, a blaster shot will probably penetrate a personal shield at least a little, and may collapse it, but most of the energy will be reradiated. Other modern weapons are less likely to penetrate, but still might; primitive weapons are generally ineffective against a shield, except for melee weapons with shield generators.

Energy that impinges on a larger portion of the shield (as in a glancing blow) is more easily dealt with; declivities in the shield surface, which force the shield to reradiate at itself, are more easily penetrated. Accuracy therefore does have some effect on shield penetration.

The other type of weapon important to the genre (IMHO) is the continuous-wave ("beam") laser, which is not as powerful as a blaster but rewards skill in keeping the beam on target, or in waving it across lots of targets.

Desired Game Effects

Important goals accomplished by the foregoing are: PCs able to survive at least one shot from a high-tech energy weapon, martial arts remaining viable in an environment with high-tech energy weapons, half-naked alien princesses.

This being ostensibly a simple system, the effects of being shot with a weapon should fall into a few categories: Only A Flesh Wound, Hurt But Still Fighting (ie, impaired), and Down. Down has some subcategories (unconscious, lightly dead, unrevivifiable), but those can be sorted out after combat. Hurt But Still Fighting should probably have lethal and nonlethal categories as well.

Some number of flesh wounds should add up to impairment, and a small number of impairing wounds (perhaps as few as two) should put the victim down.

Accuracy (ie, skill) should affect the results of an attack, which means more skill produces more damage (on average). Since, ideally, any attack (or any other action) should be resolvable by one roll of the dice, degree of success will be based on the amount by which the roll was made (roll+skill-difficulty). This means that defending/dodging attacks and absorbing damage have to be based on fixed numbers, not die rolls; only the attacker rolls.

Automatically equating the damage of an attack with its ability to penetrate armor gives me hives, but that then is at least two axes of improvement that need to be determined by a single margin of success number. So, the active player (attacker, in this case) can allocate the margin of success among whatever sorts of improvement are available, after the roll.

The degree to which a wound ruins the victim's life can be decomposed into the depth of the wound, the width/messiness of the wound, and, very importantly, the location of the wound. When quantifying this, the result is probably the product of those quantities (with location being abstracted into a single number), so in an (allegedly) log-scaled system, which is what I almost always favor, the total hosedness is the sum of the values of those three quantities. Wound depth goes as penetration, which we already need to know to figure out whether the target's shield holds. Messiness is then a second weapon stat, which should be scaled to be 0 for the most common weapon in the game (probably Medium Blaster Pistol). Location is based on the margin of success of the attack roll.

For extra realism-like fun, there should be a maximum penetration that can be added into the damage result, based on the size of the target.

We will assume that some equivalents of penetration and messiness exist for blunt/impact attacks, like the martial arts that we worked so hard to preserve.

By the description of shields, penetration can be improved somewhat by hitting the right spots, or at least not decreased by hitting the wrong spot (ditto for armor, if it comes up), so success can be allocated to increasing weapon penetration, up to a point. Success can also be allocated to the location component of damage, more or less unlimitedly. Beam weapons probably have less base damage than pulse weapons, but convert success to extra damage at a higher rate of exchange or something.


Character definition is in terms of skills, which are broad areas of skill. There are five levels of skill: Deficient, Unskilled, Competent, Expert, and Master. The default level of skill for a PC is Unskilled; a PC is only Deficient at a skill if she has specifically taken it as a disad. Normal people range from Deficient to Competent, and highly trained and experienced individuals may reach Expert, but only the very best reach Master level.

Each level of skill gives a modifer to use of that skill, a base target number for uses of that skill against the character, and the target number if the character is actively resisting or defending. See the chart below.

Example skills: Gun Combat, Martial Arts, Leadership, Athletics, Charm, Survival, Pilot, Datasystems, Engineering, Deceit. Each of these covers pretty much all reasonable activities that might be classified under that skill.

A skill can be specialized, which lets it count as one level higher in a limited subset of the field. Some examples might be Charm (Seduction), Pilot (Grav Flyers), Deceit (Disguise), or Martial Arts (Rapier).

Action Resolution is done according to the roll of two six-sided dice. Any given task has a target number, which the roll plus the appropriate skill modifier must equal or exceed in order to succeed at the task.

The difference between the roll and the target number is called the outcome. If the outcome is 0, the action is only marginally successful; otherwise, each three full points of outcome generates one success point. Success points can be used to improve the winningness of the action beyond the base level (that produced by an outcome of 1-2) in various ways depending on the kind of action. One improvement that applies to almost any action is time: 2 successes halve the time required to perform the action (or double the length of time the action is effective, as appropriate).

For actions that are not resisted by anything in particular, the GM sets the target number according to his own best judgement. A character of a given skill level will be challenged (50/50 chance of success) by a target number of 7 plus her skill modifier. 4 + skill mod is fairly easy (92%), and 10 + skill mod is quite difficult (17%). 1+ and 13+ are trivial (100% success) and impossible, respectively.

An action that is resisted by another character has a target number depending on the level of skill that the target uses to resist. If the target is actively doing something to resist (this usually requires an action point), use the active defense number; if the target is unaware of the action being taking against her, or otherwise unable to do anything about it, use the passive defense number.

For actions that are equal contests (eg, a race) both or all contestants roll against no particular target number and the highest roll wins. If the outcome matters, it's the difference between the winner's and runner-up's roll. (This can be generalized in the obvious fashion if places other than first are important.)

Deficient Unskilled Competent Expert Master
Skill Mod -3 +0 +3 +6 +9
Passive Def 6 7 8 9 10
Active Def 7 10 13 16 19

This file was last modified at 1025 on 22Aug00 by trip@idiom.com.