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Skills & traits

When you start a new 1.13 campaign, the Initial Game Settings screen asks you to pick a Skill Traits system: Old or New (see New-game options). Old keeps the vanilla-style skill list. New replaces it with a completely redesigned system of major and minor traits, originally created by community developer Sandro as S.T.O.M.P. — "Sandro's Traits and Other Modifications Project" — released as a separate mod in January 2010 and afterwards merged into 1.13 itself. Every current release ships it built in.

The choice is per campaign and cannot be changed mid-game. There is no INI switch for it; the closest thing is the optional ja2_sp.ini file that presets the new-game screen (key SKILL_TRAITS — see Presetting your defaults). Almost everything else about the new system is configurable, in Data-1.13\Skills_Settings.INI.

New traits need XML profiles (Profex)

Ja2_Options.INI states: "You must have the Profex ACTIVATED to be able to play with the NEW TRAIT SYSTEM!" — that is, READ_PROFILE_DATA_FROM_XML = TRUE, so merc data comes from TableData\MercProfiles.xml instead of the old PROF.DAT. This is the default in current releases, so you normally never have to touch it.

What changed compared to vanilla

  • Major/minor split. The old flat skill list is divided into 10 major traits (professions such as Sniper, Doctor, Squadleader) and 13 minor traits (knacks such as Athletics, Night Ops, Stealthy).
  • Two levels for major traits. Picking a major trait twice gives the expert version with a different name and roughly doubled bonuses (Sandro: "numbers are doubled for experts if not said otherwise"). Minor traits have a single level.
  • Baseline penalties. Without the matching trait, many actions are slightly worse than in vanilla — small chance-to-hit penalties per weapon class, slower doctoring and repairing, harder skill checks. The matching trait cancels the penalty and then adds a bonus on top. In Sandro's words, "these penalties represent the 'lack of knowledge' without proper trait". They only apply if you chose New Traits.
  • Everything is externalized. All numbers live in Skills_Settings.INI and can be tuned without touching the exe.
  • Everyone plays by the same rules. Enemies and militia can get traits too (see below), and their equipment is matched to their traits.
  • Personalities were reworked as well. The old attitudes/personalities became character traits (each with an advantage and a disadvantage) and disabilities (purely negative, but worth bonus points at IMP creation).

Traits are fixed: they never change, cannot be learned later and cannot be lost. You can see a hired merc's traits in the laptop's Personnel screen, and every trait on the IMP creation screen has a detailed tooltip — hover over it.

The old system

If you select Old skill traits you get the vanilla-style list, with each skill available at normal or expert level: Lockpicking, Hand-to-Hand, Electronics, Night Ops, Throwing, Teaching, Heavy Weapons, Auto Weapons, Stealthy, Ambidextrous, Thief, Martial Arts, Knifing, Sniper and Camouflage. According to the old 1.13 wiki the Thief trait is unused and gives no benefit at all. A few Ja2_Options.INI settings apply only to old-trait games and say so in their comments — for example MORTAR_CTH_DIVISOR and TEACHER_TRAIT_EFFECT_ON_LEADERSHIP are both marked "only used if Old Trait System is played".

The rest of this page describes the new system.

How the new system works

Trait slots

Defaults from the [Generic Traits Settings] section of Skills_Settings.INI:

Setting Default Meaning
MAX_NUMBER_OF_TRAITS 10 Maximum skill traits a player merc can have (2–30 allowed).
NUMBER_OF_MAJOR_TRAITS_ALLOWED 5 Major-trait slots for player mercs.
MAX_NUMBER_OF_TRAITS_FOR_IMP 3 Trait picks when creating an IMP.
NUMBER_OF_MAJOR_TRAITS_ALLOWED_FOR_IMP 2 Major-trait slots at IMP creation.
SET_MINIMUM_ATTRIBUTES_FOR_TRAITS TRUE Traits enforce minimum attribute values when selected.

So with defaults, an IMP picks up to three traits: two major and one minor, one major and two minors, three minors — or one major twice for its expert version. Mercs from A.I.M. and M.E.R.C. come with whatever their profile defines. Per the INI, enemies and militia "have always 2-3 traits max".

Expert majors have their own names

Each major trait has a different display name at level one and at expert level:

Level 1 name Expert name
Auto Weapons Machinegunner
Heavy Weapons Bombardier
Marksman Sniper
Hunter Ranger
Gunslinger Gunfighter
Hand to Hand Martial Arts
Deputy Squadleader
Technician Engineer
Paramedic Doctor
Covert Ops Spy

(The section names in Skills_Settings.INI mostly use the expert names.)

Baseline penalties without the trait

These [Generic Traits Settings] modifiers apply to everyone in a new-traits game; the matching trait compensates them. Chance-to-hit modifiers by weapon class: assault rifles, rifles, SMGs, shotguns, pistols and machine pistols −5; sniper rifles and LMGs −10; rocket and grenade launchers −25; mortars −60; throwing knives −15; thrown grenades −10; hand-to-hand attacks −15 and knife attacks −10 (with matching dodge penalties of −10). Firing two guns at once costs both shots 25% CtH (DUAL_SHOT_CTH_PENALTY), which the Ambidextrous trait removes. Controlling the robot has a −10 CtH modifier that Technicians compensate.

Assignments are slower too: doctoring, bandaging and repairing −25%, militia training −10%, teaching −15%, and lockpicking checks −10. Explosives-related skill checks (attaching detonators, planting explosives, disarming traps, attaching "special" items) are 15 points harder. Tanks get +40% damage resistance "to make Heavy Weapons trait more useful", and the damage needed to cause stat loss was halved to 15 — because doctors can now repair lost stats.

Major traits

The numbers below are the current defaults from Skills_Settings.INI (one level of the trait; a second level roughly doubles them). The five gun traits — Auto Weapons, Heavy Weapons, Marksman, Hunter and Gunslinger — also unlock the Focus skill from the tactical skills menu (A): while focusing on an area with a gun aimed, the merc gets +4 interrupt chance against targets inside the area and double that as a penalty against targets outside it.

Auto Weapons → Machinegunner

  • +5 CtH with assault rifles, SMGs and LMGs
  • Autofire/burst CtH penalty reduced by 30%
  • Fewer "unwanted" extra bullets fired on autofire (UNWANTED_BULLETS_REDUCTION = 5)
  • −10% APs to fire LMGs on burst/auto and −10% APs to ready/raise LMGs

Heavy Weapons → Bombardier

  • +25 CtH with grenade launchers and rocket launchers, −20% APs to fire them
  • −10% APs to fire mortars; the mortar CtH penalty is halved
  • +30% damage against tanks, +15% general damage with heavy weapons

Marksman → Sniper

  • +5 CtH with rifles, +10 with sniper rifles
  • Effective range to target reduced by 5 for aim calculations
  • +10 CtH per aim click with rifles, and one extra aim click for rifles
  • +5% damage per aim click from the third click onward
  • −25% APs to chamber a round in bolt-action rifles

Hunter → Ranger

  • +5 CtH with rifles, +10 with shotguns
  • −25% APs to pump shotguns, −10% APs to fire them, +15% faster manual shell reloading
  • One extra aim click and +10% effective range with shotguns

Gunslinger → Gunfighter

  • +10 CtH with pistols, +5 with machine pistols (single shots only by default)
  • +5 CtH per aim click and one extra aim click with handguns
  • −15% APs to fire and to ready/raise pistols and revolvers, +25% reload speed
  • +10% effective pistol range
  • Can fan the hammer: revolvers flagged with <fBurstOnlyByFanTheHammer> in Weapons.xml get a hidden burst mode when wielded two-handed in hipfire mode (CAN_FAN_THE_HAMMER = TRUE)

Hand to Hand → Martial Arts

  • +30 CtH with bare hands, +25 with brass knuckles; −15% APs per punch
  • +30% hand-to-hand damage and +15% extra stamina damage to the target; knocked-down victims take much longer to start regaining energy
  • Aimed punches/spinning kicks: +50% damage per trait level on top of the normal aimed-punch bonus
  • +30% dodge against hand-to-hand, +20% against blades and blunt weapons
  • −25% APs to change stance, turn around, climb roofs and jump fences; −25% APs to steal weapons; +25% chance to kick doors open
  • Reduced chance to be interrupted when charging at an enemy (Improved Interrupt System only)
  • Special martial-arts animations are reserved for expert-level martial artists (PERMIT_EXTRA_ANIMATIONS_TO_EXPERT_MARTIAL_ARTS_ONLY = TRUE)

Deputy → Squadleader

Bonuses apply to mercs within 10 tiles (20 if both leader and merc wear extended ears); at most 3 leader bonuses stack on one soldier:

  • +5% max APs and +1 effective experience level for nearby mercs
  • +20% suppression tolerance for the leader and everyone nearby
  • +1 morale gain / −1 morale loss for nearby mercs
  • +20 bonus to triggering collective interrupts (Improved Interrupt System)
  • The leader himself resists fear (50%)

With AMBUSH_MERCS_SPREAD enabled in Ja2_Options.INI, a high-leadership squadleader also lets you deploy your mercs before entering an ambushed sector, and enemy soldiers with this trait act as officers if ENEMYROLES is on (lieutenant with one level, captain as expert).

Technician → Engineer

  • +25% repair speed; the extra penalty for repairing electronics is halved
  • +30% lockpicking (including electronic locks), +40% disarming electronic traps
  • +40% to attaching/merging items, +20% to unjamming guns
  • +2 effective level for finding hidden traps and mines
  • +10 CtH when controlling the robot; robot repair penalty reduced by 33%. By default at least one Technician trait is needed to repair the robot at all (NUMBER_TRAITS_TO_BE_ABLE_TO_REPAIR_THE_ROBOT = 1)
  • Optionally, technicians can perform "advanced repair" beyond the item threshold like local weaponsmiths (MERCS_CAN_DO_ADVANCED_REPAIRS, off by default)

Paramedic → Doctor

  • Surgery: by default requires at least one Doctor trait (NUMBER_OF_TRAITS_NEEDED_FOR_SURGERY = 1). Surgery restores 10% of lost health plus 20% per trait level (30% as Paramedic, 50% as Doctor), +15% more when using a blood bag
  • Stat repair: doctors can restore stat points lost to injuries — rate 20 + 40 per trait level (Paramedic 60, Doctor 100); healing and stat-repairing at the same time slows both by 50%
  • +25% doctor assignment effectiveness, +30% bandaging speed
  • Mercs in the same sector regenerate naturally 10% faster per Paramedic level (a Doctor counts double, at most 4 stacks)

Covert Ops → Spy

The disguise-and-infiltration trait, added by Flugente in 2012 (unlike the other majors it is not part of the original STOMP nine). Disguises are "very strongly tied" to this trait: a merc without it can only disguise as a civilian and is automatically detected when getting near a soldier. The trait enables disguising as an enemy soldier — though a merc with only the first level is still exposed when enemies get close. Key numbers from the [Covert Ops] INI section: +40 CtH and +35 instant-kill chance with covert melee weapons, −20% APs for disguising, and detection rules (enemies inspect you closely within 10 tiles, elites/officers can uncover disguised spies within 6 tiles, standing near a fresh corpse blows a soldier disguise within 5 tiles). The same section configures the turncoat recruitment system. See Covert operations for the full gameplay guide.

Minor traits

One level each. Key defaults from Skills_Settings.INI:

Trait What it does (defaults)
Ambidextrous Removes the entire 25% dual-gun CtH penalty; +20% reload speed with magazines, +33% with loose rounds; 33% faster item pickup, backpack use, door handling, bomb handling and item merging.
Melee +35 CtH with blades, +25 with blunt weapons; −20% APs per blade attack; +30% damage with both; +50% damage on aimed melee attacks; +30% dodge vs blades (+20% more when holding a blade), +20% vs blunt weapons.
Throwing Thrown blades: −20% APs, +15% range, +25 CtH (+5 per aim click), +15% damage (+10% per click), one extra aim click, 20% chance of a critical hit when unseen. Thrown grenades: +30 CtH, −25% APs, +20% range.
Night Ops +1 sight range in darkness; +1 hearing range always, +2 more in darkness; +2 interrupt bonus at night; reduced need for sleep.
Stealthy The AP surcharge for sneaking is halved; +40% chance to move silently; +25 overall stealth; −20 chance to be interrupted (Improved Interrupt System); movement is 25% less likely to reveal you. Each level also adds 15 points to your Cover System stealth value (COVER_SYSTEM_STEALTH_TRAIT_VALUE in Ja2_Options.INI).
Athletics −25% APs for movement; −33% stamina spent on movement.
Bodybuilding +25% damage resistance; +30% carrying capacity; half the stamina loss when hit hand-to-hand; twice the damage needed to be knocked down by leg hits.
Demolitions +25% damage from your bombs and mines; +50% to attaching detonators and to planting/removing explosives; your bombs are harder to detect; shaped charges are far more effective (multiplier 3).
Teaching +40% militia training speed and +40% effective leadership for it; +40% speed teaching other mercs, whose skill counts +25 higher for teaching purposes; +25% faster self-practice.
Scouting +40 sight range with binoculars and hand-held scopes (+10 with weapon scopes), −20 tunnel vision with binoculars; detects enemy presence and exact numbers in adjacent sectors; prevents enemy and bloodcat ambushes.
Radio Operator Operate a radio set: call artillery strikes and militia reinforcements, scan for enemies up to 5 sectors away, jam enemy radios, +20 hearing when listening in. See Support roles.
Snitch Informs you about events among your mercs (base 50% chance, modified by relationships and leadership); intended to build your reputation over time (currently inverted by a bug — see Reputation); +1 hearing range; can work undercover in prisons as a covert interrogator (3× interrogation effectiveness; the INI's separate guard-strength multiplier is loaded but unused in current code) — see Snitches & informants.
Survival +30% group travel speed on foot, +15% in vehicles (max 2 survivalists stack per group); −50% own stamina spent travelling; 35% lower weather penalties; camouflage wears off 75% slower and is 20% more effective; can track footprints (Ctrl+C menu); 10% disease resistance; −20% food and −10% water consumption (see Food & water); +10 bonus to evade snake attacks.

The exact numbers are all in one file

Every value above — and many more per trait — is documented with comments in Data-1.13\Skills_Settings.INI. If a bonus feels too strong or too weak, you can change it there for your next campaign.

Traits at IMP creation

Creating an IMP merc in a new-traits game works like this:

  • You pick up to 3 traits, of which at most 2 may be major; picking the same major twice gives the expert version.
  • Traits set minimum attributes (shown in brackets after the trait name on the attribute screen) as long as SET_MINIMUM_ATTRIBUTES_FOR_TRAITS = TRUE.
  • Every trait slot you leave empty is worth +35 bonus attribute points (IMP_BONUS_POINTS_PER_SKILL_NOT_TAKEN in Ja2_Options.INI), and taking a disability gives +25 points (IMP_BONUS_POINTS_FOR_DISABILITY).
  • Your starting gear depends on your traits, defined in TableData\Inventory\IMPItemChoices.xml; with EXPERTS_GET_DIFFERENT_CHOICES = TRUE (the default), expert traits get their own gear entries.
  • If ALTERNATIVE_IMP_CREATION is enabled in Ja2_Options.INI (off by default), your choices of skills, character traits and disabilities filter which backgrounds are offered — backgrounds whose tags contradict your picks are hidden, and extra backgrounds become available to compensate. Backgrounds live in TableData\Backgrounds.xml.

Character traits and disabilities

STOMP also replaced the vanilla attitudes and personalities. Character traits each combine a small advantage with a small disadvantage — about 5–10%, "not meant to boost your mercs, but just to diversify them more": Sociable, Loner, Optimist, Assertive, Intellectual, Primitive, Aggressive, Phlegmatic, Dauntless, Pacifist, Malicious, Show-off and Coward — or plain Normal. For example, an Aggressive merc hits better on autofire and gains morale from kills, but is worse at patient work like repairing, doctoring and lockpicking.

Disabilities are purely negative quirks (in return for IMP bonus points). STOMP made Heat Intolerant actually work (penalties in desert and tropical sectors when it isn't raining), changed Fear of Insects, and fixed the Psycho disability, which in the old system gave an absurd hidden CtH bonus.

Traits on enemies and militia

From Ja2_Options.INI ([Tactical Difficulty Settings] section):

ASSIGN_SKILL_TRAITS_TO_ENEMY = TRUE
ASSIGN_SKILL_TRAITS_TO_MILITIA = TRUE
ASSIGNED_SKILL_TRAITS_RARITY = 0

The game matches traits to equipment — "an enemy with LMG will most probably have Auto Weapons trait (no way he can be a sniper for instance)" — and the chance depends on soldier type (admin/regular/elite), game progress, special equipment and the rarity setting (−100 to 100; negative means fewer traits). The INI warns that enemies with traits make the game significantly harder, especially with new traits. Militia benefit the same way; see Militia.

Files that tune the system

File What it controls
Data-1.13\Skills_Settings.INI All new-trait numbers: generic penalties, one section per trait. In the very first STOMP releases this file was called Traits_Settings.INI.
Data-1.13\Ja2_Options.INI IMP creation points and gear switches, enemy/militia trait assignment, background options, cover-system stealth value, ambush/officer interactions, plus a few old-system-only settings.
TableData\MercProfiles.xml Which traits each AIM/MERC/RPC merc has (requires Profex).
TableData\Inventory\IMPItemChoices.xml Starting gear per chosen trait (separate entries for experts).
TableData\Backgrounds.xml Backgrounds and their interaction with IMP trait choices.

See the configuration overview for how these files are layered and edited safely, and XML files for the TableData folder.

Sources