"Mass Effect RPG" - A Campaign Setting for Stars Without Number

edited March 2012 in Story Games

Hey there--
Based on comments made by the SWN game author here, and readily available information about Mass Effect from here, I've taken a stab at writing up an SWN campaign guide for the Mass Effect universe. This campaign guide mostly assumes that you are running a game after the events of the video game trilogy. Consequently it includes rules for travelling across the galaxy without the Mass Relays should that be necessary...

Give it a read and let me know what you think.


Using Stars Without Number for Mass Effect RPG

These are my house rules for using the Mass Effect setting in Stars Without Number.

PC Races

The Mass Effect universe consists of several sentient races. There are race-specific bonuses, but there are also attribute requirements to play a given race. Also note that non-human races are less adaptable and are thus restricted as to which classes they can take:

Race Available Classes Required Attribute Racial Bonus
Human All None None
Asari Adept, Vanguard 14+ WIS or DEX -1 Mental Effect Save
Drell Adept, Vanguard 14+ CON or DEX -1 Evasion Save
Krogan Soldier, Sentinel 14+ STR or CON -1 Physical Effect Save
Quarian Engineer, Infiltrator 14+ INT or DEX -1 Tech Save
Salarian Engineer, Infiltrator 14+ INT or CON -1 Mental Effect Save
Turian Soldier, Sentinel 14+ STR or INT -1 Luck Save

Starting Level and Mass Effect Classes

All PCs start at level 2 and choose from the following ME classes:

ME Class Base Classes1 Base Combat Skill Proficiencies2
Soldier Warrior x 2 Pistols, Shotguns, Assault Rifles, Sniper Rifles, Heavy Weapons
Adept Psychic x 2 Pistols, Submachine Guns, Heavy Weapons
Engineer Expert x 2 Pistols, Submachine Guns, Heavy Weapons
Vanguard Warrior, Psychic Pistols, Shotguns, Submachine Guns, Heavy Weapons
Sentinel Expert, Psychic Pistols, Submachine Guns, Heavy Weapons
Infiltrator Expert, Warrior Pistols, Sniper Rifles, Submachine Guns, Heavy Weapons

Bonus Skills
All PCs start with the Exosuit skill at Level 0.

Levelling and Multiclassing

All PCs use the Psychic XP table for advancement:

Level XP
1 0
2 2,005
3 4,010
4 8,020
5 16,040
6 32,080
7 64,160
8 128,320
9 250,640
10 370,000
11+ +125,000

When the PC goes up a level, they can take the level from either base class that comprises their ME class. The PC gains whatever skill points, psi power points, or psychic disciplines they might earn from the level, but keep the skill points granted by each class separate. They can spend skill points earned in any class on learning a given skill, but if it’s not a class skill for all of them it costs non-class advancement rates. Vanguards, Sentinels and Infiltrators use the better saving throws and attack bonuses from either of their base classes, and gain all the class abilities for each class they have (except for their starting Special Ability, as noted above in Starting Level and Mass Effect Classes)

Class Modifications

The base classes are unchanged except for the Psychic class.

  • Psychic abilities are referred to as "Biotic" abilities
  • Biotics do not have a primary discipline and can spend both of their 2 points per level as they wish.
  • The disciplines of Biopsionics and Teleportation do not exist.

Skill Modifications

The following skills have been revised to align with weapons of the Mass Effect universe:

The combat specialties are as follows. PCs start with level-0 proficiency in these skills as indicated by their ME class:

  • Unarmed: All legal items from the Primitive Weapons and Unarmed Attacks table (p. 36)
  • Pistols: Crude Pistol, Musket, Revolver, Semi-automatic Pistol, Mag Pistol
  • Shotguns: Shotgun, Combat Shotgun, Spike Thrower
  • Submachine Guns: Submachine Gun, Void Carbine
  • Assault Rifles: Rifle, Combat Rifle, Mag Rifle
  • Sniper Rifles: Sniper Rifle
  • Heavy Weapons: All legal items from the Gunnery Weapons table (p. 40)


  • "Pretech" is "Prothean" tech
  • There is no "Psitech"

Weapons and Combat

PCs apply a -2 penalty to hit when using any weapon with which they are not proficient (as per their ME class, above).

Weapon Ammunition and Weapon Overrides
Standard (non-Heavy) projectile weapons in the Mass Effect universe do not require ammo, but instead use coolant cartridges to prevent from overheating. The result is functionally identical to conventional firearms. However, in an emergency, a PC can attempt to override the safeties and use the weapon until it overheats. The modification requires a DC 9 Combat ([Weapon Class]) or Tech (Postech) skill check. The attempt takes a full round. Repairing the weapon to function normally again requires 5 minutes, appropriate tools, and another DC 9 Combat ([Weapon Class]) or Tech (Postech) skill check. Only one attempt can be made to repair the weapon; failure leaves the weapon unusable.

While overridden, the weapon can fire every round without reloading. The overheat threshold starts at 1 and increases by 1 with every consecutive round of weapon use. On any attack where the face value of the d20 is equal to or less than the threshold value, the weapon overheats. If the d20 roll is equal to or lower than the threshold value minus five, the weapon fuses and is no longer useable. If the weapon is not fired in a given round, the overheat threshold resets to 1.

Equipment Availability

The following equipment restrictions apply to the Mass Effect universe.

Tech Level
Starting PCs can have any starting equipment from Tech Level 4 or lower except as specified below.

Unavailable Equipment by Type
The following equipment is not available to starting PCs or simply not available in the Mass Effect universe, as indicated:

  • Primitive Weaponry: Monoblades3
  • Energy Weaponry: All3
  • Psitech Weaponry: All4
  • Gunnery Weapons: Wheatcutter Belt 4
  • Exploration Gear: Vacc Skin3
  • Tools and Medicine: Bioscanner, Metatool (see Omnitools below), Lazarus Patch (see Medigel below)
  • Personal Accessories: Compad, Dataslab, Holo Unit (see Omnitools below)

Medigel is a formulation of antibiotics, coagulants, system stabilizers, plasma, and a one-shot diagnostic suite. Medigel automatically heals 1d8 + CON damage, but adds 1 point of System Stress with each use. If medigel is applied to a character that has fallen to 0 hit points, the administrator can make a Tech (Medical) skill check against DC 6 to stabilize the subject. The more time between injury and application, the less chance the medigel has to work. Each round after the first, an additional -1 penalty is applied to the skill check. Medigel is no use on a fallen character after six rounds. If the administrator fails the first skill check, they can keep trying the check once per round until the victim is revived or time runs out.

All armor is designed to carry up to six medigel doses. Using these doses is not automatic, and requires a regular action.

All PCs carry an omnitool, which is a small portable computer and holographic display unit built in to a gauntlet worn on the PC's off-hand. The omnitool provides bioscanner, metatool, compad, dataslab and holo unit capabilities as per the standard SWN rules. Additionally, the omnitool can project or retract an energy blade as a free action. This blade has no tangible substance, but if brought into contact with any creature or object, it does 1d4 points of damage. The omnitool attack ignores armor. Attacks made with it use the PC's Combat (Unarmed) skill. Omnitools run for 24 hours on a Type 'A' power cell. (Type 'A' power cells can be fully recharged in 30 minutes)

If the PC's Combat (Unarmed) skill is 2 or higher, the PC can add their Combat (Unarmed) skill value and Strength bonus to the damage dealt by the omnitool.

Starship Travel

There are three scales of travel:

This is any travel amongst planets orbiting around a common gravity source (star, black hole, etc.). In-system travel uses negligible fuel. At this scale, the drive rating only serves as an indicator of the ship's relative speed.

This is Faster-Than-Light (FTL) travel between closely grouped systems. At "cluster scale", a ship burns through 1 full fuel load and 24 hours to travel a number of hexes equal to the ship's drive rating. Thus, a ship with drive rating 2 covers twice as much distance as a ship with drive rating 1 in the same 24-hour period and the same relative fuel load. Each extra fuel bunker adds 1 additional fuel load, increasing the ship's total range accordingly.

This is travel between the dozens of star clusters scattered throughout the galaxy. The Mass Relays make galactic travel trivial--negligible ship fuel is consumed and transit time is 24 hours per galactic hex. Generally there is one Mass Relay per star cluster.

If not traveling by Mass Relay, each galactic hex must be treated as the equivalent of 100 cluster-scale hexes for the purposes of computing fuel requirements and transit times. Thus, traveling from one galactic hex to a neighboring hex is the equivalent of 100 cluster-scale hexes, and traveling from one galactic hex to a hex six steps away is the equivalent of 600 cluster-scale hexes5.

Starship Combat

Starship Combat is as described with one exception. There is no Spike Phasing in the Mass Effect universe. Thus ship encounters are typically brutal and brief.

  1. Vanguards and Sentinels take the "Psychic Powers" Special Ability. Infiltrators choose "Like a Charm" or "Veteran's Luck" 

  2. These Combat Skill Proficiencies supersede any Combat Skill Proficiencies granted by the base class. Skills granted through background packages may stack with these as normal. See the Skill Modifications section for more information on these. 

  3. These items are not available to starting PCs but may be found in the Mass Effect universe; they all count as Prothean technology and are exceedingly rare. 

  4. Psitech and psitech weaponry are not available in the Mass Effect universe; wheatcutter belts are also not available. 

  5. Only a carrier-sized ship with a class-6 engine could attempt such a journey without entering a system to refuel, provided that every available free mass point on the carrier was used for fuel bunkers. The six-galactic-hex journey would take a year and 8 months and 100 successful jump checks. 


  • Very slick. I've never run Stars Without Number, but this makes me want to.
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