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Drugs & disease

1.13 turns two of vanilla JA2's throwaway systems into deep, interconnected mechanics. Drugs are a flexible item type: anything from a shot of adrenaline to a cheap beer runs through the same data-driven engine, complete with side effects, disabilities and addiction. Disease is a fully optional system (off by default) that lets your mercs catch everything from typhoid to Ebola, spreads plagues through Arulco's civilian population, and even enables crude biological warfare.

The two systems are linked: most stimulants feed "addiction" points into the disease engine, alcohol causes hangovers, and cigars cause lung cancer — but those consequences only bite when the disease system is switched on.

Drugs

What counts as a drug

A drug is any item flagged as medical with a DrugType value that points at an entry in Data-1.13\TableData\Items\Drugs.xml. That covers a lot more than syringes:

  • Combat stimulants — Energy Booster, Stim, Barrage, Reflex, Regen Booster.
  • Alcohol — spirits (40%), wine, beer, each with its own strength.
  • Everyday consumables — Coffee, Energy Drink, Soda, Cigar, Painkiller.
  • Weaponized effects applied when a target is hit — the M99 tranquilizer, a neurotoxin dart, and even the "high-capacity bullet" trauma effect.
  • Cures — Plague, Tetanus and Cholera medicine (see below).

Food can double as a drug

Energy drinks, coffee and soda are both food and drug items: they quench thirst through the food & water system and give a mild stimulant kick through the drug system at the same time. Nothing stops a modder from making a sandwich that heals or a canteen that gets you drunk.

Effects and side effects

Each drug in Drugs.xml is built from one or more effect blocks. A DRUG_EFFECT block raises or lowers a stat for a number of turns:

Effect What it changes
HP Health points
BP Breath / energy
AP Action points
Morale Morale
Physical resistance Damage resistance
STR / AGI / DEX / WIS The four physical/mental stats

A block can also carry a <chance> so an effect only sometimes fires. On top of stat changes, a drug can attach:

  • DISABILITY_EFFECT — a temporary disability such as psycho, nervous, claustrophobic or forgetful for the duration.
  • PERSONALITY_EFFECT — a temporary personality/character-trait shift.
  • DISEASE_EFFECT — adds (or removes) points of a disease from Disease.xml.

Side effects are baked into the stock drugs. A few examples from the shipped data:

  • Stim gives big breath, resistance and strength boosts, but almost always turns the merc psycho and malicious for the duration.
  • Alcohol raises breath and morale but can lower wisdom, and — at higher doses — rolls on a long list of random personality changes and a chance of a temporary short-sighted disability.
  • Barrage is a strength/resistance drug with a small chance to cost the user 100 breath (a simulated collapse).
  • Cigars cost a little breath for a morale bump.
  • AP-boosting drinks let a merc move more, but weapon-handling actions cost proportionally more AP, so you cannot fire faster — this is intended, long-standing behaviour, not a bug.

Addiction

When the disease system is on, most stimulants quietly add points to the Drug Addiction disease (see the disease list). Painkillers add a large amount, Stim and Regen Booster a moderate amount, an Energy Drink very little. Alcohol feeds a separate Hungover disease and cigars feed Lung Cancer. With the disease system off, these DISEASE_EFFECT entries do nothing, so drugs behave like their older, consequence-free selves.

Using drugs on yourself and others

Consume a drug the normal way — right-click it in a merc's hand to apply it to that merc. 1.13 also lets you apply an item to another person: put the drug in a merc's hand, right-click to enter the apply cursor, hover over another character and left-click. This works on your own team (to dose or heal an ally) and on the enemy — applying a drug to a hostile has a chance to fail based on your merc's experience, dexterity, the Stealth trait, the target's alert status, and the item's weight. The same mechanic handles canteens, gasmasks, clothes and even bombs; ammo and reloading are deliberately excluded as exploits.

Weaponized drugs

The M99 tranquilizer and neurotoxin dart are drugs whose whole purpose is to be delivered to a target — handy for taking a soldier alive rather than killing them. See prisoners for what to do with a knocked-out enemy.

Editing Drugs.xml

Drugs.xml lives in Data-1.13\TableData\Items and is heavily commented at the top with the full list of effect, disability and personality codes. An item is tied to a drug through the <DrugType> tag in Items.xml, which holds the drug's <uiIndex>; up to 100 drugs can be defined.

The XML Editor can't edit Drugs.xml yet

The community XML Editor lists "Drugs.xml is not working" as a known issue (0.2.2-beta). Edit Drugs.xml by hand in a text editor until that is fixed, and keep a backup.

Disease

Disease is off by default. It is a heavyweight, punishing system — your mercs can and will die of illness if you neglect them — so it is opt-in.

You need the matching game data

The disease feature relies on images and data shipped in the game folder. If you turn it on with an old or incomplete install, the game can crash when a disease assignment or icon is used. Play it on a current release so the Disease.xml and disease graphics are present.

Turning it on

Set the keys in the [Disease Settings] section of Ja2_Options.INI:

Setting Default What it does
DISEASE FALSE Master switch. Your mercs can catch diseases from Disease.xml.
DISEASE_STRATEGIC TRUE Only matters if DISEASE is on. Spreads disease through the civilian population and makes vanishing corpses a health hazard.
DISEASE_WHO_SUBSCRIPTIONCOST 2000 Daily cost to subscribe to the World Health Organization outbreak map. Requires the two settings above.
DISEASE_CONTAMINATES_ITEMS TRUE Food and blades used by a plague carrier become contaminated and infect the next user.
DISEASE_SEVERE_LIMITATIONS FALSE Unlocks harsher effects: extra permanent disabilities, one-hand-only use, and crippled legs (no kicking/running, much slower travel).

How mercs get sick

A merc is infected through one of several routes, each with its own per-disease chance:

  • Swamp and tropical sectors — dirty water and biting insects.
  • Wounds — animal bites, open/gunshot/fire/gas wounds, and critical hits that cost a stat (AGI/DEX/STR/WIS) can leave lasting maladies.
  • Traumatic events — psychological harm, not just physical.
  • Spoiled food and stale water — quick and nasty; this route needs the food & water system running.
  • Human contact — many diseases pass between people, so one sick merc can infect the squad. A doctor treating a patient is at much higher risk.
  • Corpses — handling the dead is an excellent way to catch something.

Progression, symptoms and detection

An infection often lingers unnoticed, then breaks out later and grows toward a maximum; symptom strength scales with how far a disease has progressed. Once a disease breaks out you always know what it is (you get a message, and it shows on the merc's portrait and in the strategic screen). Possible symptoms include:

  • Lowered effective AGI/DEX/STR/WIS and effective level.
  • Lowered action points and maximum breath.
  • Reduced carrying capacity and a greater need for sleep.
  • Sharply higher food and water use (simulating vomiting and dehydration, with the food system on).
  • Morale loss, and disgust from teammates if you play with dynamic opinions.
  • Reduced — even negative — health regeneration, which can kill an untreated merc.

Waiting for an outbreak is dangerous. Assign a skilled medic to the Diagnosis assignment to catch diseases before they break out. The per-check detection chance is roughly ((med skill / 2) + (doctor trait level × 20)) × (100 + background modifier) / 100, so anyone can do it but medical personnel are far better at it.

Treatment

  • Doctors. The normal Doctor assignment cures most diseases on your own mercs, restoring lost infection points and then healing further.
  • Medications. Some illnesses have a dedicated cure item — Plague, Tetanus and Cholera medicine are drugs whose only job is to remove points of a specific disease.
  • Symptom control. A few diseases (Ebola, for one) cannot be cured. You can only treat the symptoms — order a doctor to restore the health they are draining — and wait for the disease to burn itself out.
  • Protective gear. A facemask or gasmask worn in the face slot cuts infection by human contact and corpses by up to 50% depending on its condition; keeping gloves in your inventory cuts it by a further 50%. New character backgrounds add modifiers to disease resistance, diagnosis and treatment effectiveness.

The disease list

The shipped Disease.xml defines 20 diseases (up to 20 are supported). Every property — infection chances, symptoms, whether it can be cured — is data-driven, so a modder can retune these or invent their own.

# Disease Curable Notes
0 Arulcan plague Yes The strategic-layer plague; spreads through the population.
1 Typhoid Yes Mainly from unclean water.
2 Hepatitis A Yes Reverses once it peaks.
3 Tetanus Yes Cured by tetanus medicine.
4 Tuberculosis Yes
5 Cholera Yes Cured by cholera medicine.
6 Ebola No No cure; extreme dehydration and health loss, but reverses on its own.
7 Malaria Yes
8 Staphylococcus No
9 Chlamydia Yes
10 Ballistic trauma No Inflicted by heavy gunshot wounds.
11 PTSD No Permanent; from traumatic events.
12 Broken leg No
13 Broken arm No
14 Wounded biceps No From a chest hit; can re-infect and fades over days.
15 Drug Addiction No Fed by stimulant drugs.
16 Hungover No Fed by alcohol.
17 Lung Cancer No Fed by cigars.
18 Burns No
19 Corroded lung No

Strategic disease and epidemics

With DISEASE_STRATEGIC on, one disease (by default the Arulcan plague, disease #0) also spreads through the wider population. The game estimates how many civilians live in each sector from the usCivilianPopulation value in SectorNames.xml — far more than the handful you meet in a tactical map.

  • Enemy patrols pick the plague up in swamps and tropics and carry it between sectors, seeding towns and other patrols until an epidemic brews.
  • When you enter an infected sector, some civilians, soldiers and militia will show the disease's symptoms, including lowered health — which can make a fight easier. Their health is never dragged below a floor, so they won't simply die of it.
  • A sick workforce mines less, so an outbreak can cut your mine income.
  • Your mercs infect the population and vice versa, so isolating a sick merc matters.

You clear a sector's population with the Disease → Treatment assignment (this treats civilians, not your mercs), and remove vanishing corpses — a source of "disease points" — with the Disease → Burial assignment. The enemy army will also fight disease it notices, using its medics.

To find out where disease is spreading, use the Diagnosis assignment (it can spot sector infection too) or subscribe to the World Health Organization. For the daily DISEASE_WHO_SUBSCRIPTIONCOST, the WHO unlocks a strategic map mode that colours sectors by how much of the population is infected and shows the mean infection level — though it only reveals outbreaks that have been noticed, so a quiet sector isn't guaranteed clean.

Biological warfare

DISEASE_CONTAMINATES_ITEMS opens up deliberately nasty tactics. If a merc carrying the Arulcan plague (even before they know they have it) eats from a food item or canteen, that item is contaminated and infects the next person to use it — including the carrier again after they are cured, so throw out a cured merc's food and canteens.

The same applies to blades and throwing knives: a blade that hits an infected person, or is used on a corpse, becomes contaminated and infects whoever it strikes next. A covert-ops spy can slip into an enemy town, seed the plague days before your assault, and walk out clean. Killing an enemy sector's medics stops the AI from treating disease there for 12 hours — cumulative up to 60 — so a well-timed outbreak can overwhelm a garrison before the assault even begins.

It's your plague once you take the town

A city you conquer keeps whatever disease you seeded in it. Bring extra doctors, or your victory sector becomes a liability.

Version notes

Flugente first overhauled the drug system in 2012, when it let you build custom drugs from components; it has since been reworked into the entry-based Drugs.xml described here, tied into the disease engine. The disease system was added in 2014 (SVN r7384 / GameDir r2099) and has grown to today's 20 diseases and drug integration. Both are stock features of current 1.13 releases; only the INI toggles above and the XML data differ.

Sources