GURPS uses an advantage (and enhancement) system for powers, while it generally uses a skill (and maneuver) system for martial arts. This is not necessarily wrong, but I thought it would be an interesting exercise to try and come up with a way to do many powers using the skill and maneuver system. SBS is the result.
The basic mechanic of SBS is very simple: you have a small number of super-skills, and then you have techniques off of those skills. Techniques, in turn, come in two flavors: basic techniques, which are used directly, and variable techniques, which may be stacked on to a basic technique. Whenever you use a super-skill, you must pick exactly one basic technique, and any number of variable techniques. Techniques have difficulty as follows:
Basic Technique: default is -1 per 10% net enhancement, or +1 per 10% net limitation, plus any Special modifiers; max is Default+5.
Variable Technique: default is twice the basic technique, or -1, whichever is worse. Max is equal to the default for the basic technique. Thus, an AP(2) technique (50% enhancement, or -5 on a basic technique) has a default of -10 and a max of -5.
Super-skills generally require Innate Attack skill to hit; if they hit, you roll the super-skill to determine the effect.
The Damage super-skill lets you do damage (does not grant the ability to hit; use Innate Attack for that). A basic technique must incorporate a damage type, and does damage equal to your margin of success; technique difficulty depends on damage type:
Special Technique: Affliction: +0 default. Rather than doing damage, applies an affliction. The duration of the affliction (seconds for stunning, minutes for other effects) is equal to the damage the attack would have done, after applying defenses; targets with 20+ hit points which are not using Durability divide duration by (HP/20). Most afflictions are based on Toxic damage.
Special Technique: Increased Damage Multiplier: -10 or more. Multiplies MoS. Default is -10 + 5*(multiplier on the size chart) -- so -10 for x2, -15 for x3, -30 for x10, -60 for x100.
Special Technique: Secondary Attack: -4/-9 or -6/-6. This power generates two simultaneous effects, which are resolved separately against defenses, and have their own skill levels. This has a split penalty; apply one modifier to the primary effect, the other modifier to the secondary effect. When resolving this attack, use the same die roll for both techniques.
Special Technique: Use Weapon (Melee/Thrown): fixed technique only, +0 default. Allows attacking with a ST-based weapon. Your skill is modified by any advantages on the weapon; thus, if you use a sword (cutting), you'll be at -4, if you use a hyperdense sword (cutting, AP/10) you'll be at -24. You must learn separate techniques for melee and thrown weapons.
This skill is the reverse of Super-Skill: Damage. Make a roll, as per Damage skill; your margin of success indicates the amount of DR you provide. If you fail to stop the entire attack, you take damage equal to your margin of failure.
Special Technique: Multiple Defenses: +0. Your power provides two different sorts of DR, with different modifiers, and potentially different skill levels.
This skill also functions to resist damage, but applies after DR; unlike SS:DR. Look up the total injury you took on the Damage chart; the indicated MoS is a penalty to your Durability roll. A successful roll reduces damage to 1; a critical success or success by 10+ reduces it to zero; a failed roll means you take damage equal to the amount by which you failed. It is not possible to mix durability effects; if you have several techniques, use whichever is best.
Force techniques allow manipulating objects; they are modified based on the target's weight.
A creature or vehicle can be estimated as having a penalty of -10 - SM*5. A boulder might give an additional -10 to -15. The major techniques of Force are as follows:
Basic Technique: Grapple. +0. If you succeed in your roll, the result is the penalty to the target's DX or Escape roll to get away. Alternately, the target may resist with ST; your grapple has an effective ST equal to the amount by which you made the technique roll without modification for target weight.
Basic Technique: Move Object. +0. If you succeed in your roll, look up the result on the table for the Damage super-skill, and that is the speed, in hexes per turn, with which you can move the object. Move Object technique may not exceed your Damage skill.
Special Technique: Mass-Scaled. +0; may be learned arbitrarily high.
. Rather than adjusting skill based on weight,
Most powers have a source of some sort, be it cyberware, or magic, or psionics, or superpowers. Source is intended to represent this. However, it is a much larger modifier than source limitations in Supers, because it has a secondary purpose of balancing powers with other setting capabilities.
Source: variable, max by campaign (see text).
You have powers which draw from a particular source, and gain benefits from that source. It is normally fairly obvious that you have a source; disguise (or sometimes holdout) allows you to conceal a source you are not using, but concealed sources are used at a -5 penalty. A source normally has a legality class of (setting TL) - (bonus/5); the GM should set the maximum value of a source based on how legal he wants powers to be (these values may need adjustment below TL 5). A high magic setting should generally be interpreted as TL 3+3 or so. All powers with sources are subject to specific countermeasures, as defined by the GM. Source bonuses don't apply to anything that couldn't reasonably be done with that source, and that some sources may require unusual background modifiers.
Inobvious Source: -1 to -10
Your source is less obvious than normal; Per rolls to find the source are at a penalty equal to the inobvious source penalty.
Invisible Source: -10
Your source cannot be detected by normal vision, though there will be special equipment or abilities that can do so. A source that is both invisible and inobvious gives penalties to sensor rolls (or detection spells, or whatever is being used). Invisible source as a variable source can be used to represent a costume: when you aren't wearing the costume your source is invisible and you take a -10 penalty, when you're hiding your costume you take a -5, when you're in full costume you get a +0. If you have shapeshifting, powers that are only usable in your alternate form as as obvious as your alternate form.
Obvious Source: +1 to +5
Your source is very hard to conceal, and gives a -1 to -5 penalty to rolls to conceal it. Cannot be combined with invisible.
All source modifiers can be taken as variable or fixed techniques.