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AP & BP tuning

Data-1.13\APBPConstants.ini is the price list of tactical combat. Almost every action a soldier can take in a turn — stepping onto a tile, dropping to a crouch, kicking a door, reloading a single round, handcuffing a prisoner — has its Action Point (AP) cost defined here, and most actions also have a Breath Point (BP) cost that drains the energy bar. Where Ja2_Options.INI decides which rules are active, this file decides how fast everything happens, which makes it the main lever for the pacing and feel of turn-based combat.

The file has two sections, [APConstants] and [BPConstants], and like the other 1.13 INIs it documents itself: every key sits under a comment block explaining what it does. This page is a guided tour of the settings worth knowing about, not a dump of every key — for the full list, open the file itself. If you play a mod with its own data folder, edit that folder's copy instead; see the configuration overview for how the data folders stack.

Action points on the 100-point scale

Action points are JA2's currency of time: each soldier gets a budget per turn and every action spends from it. The original game handed out roughly 10 to 25 APs a turn; 1.13 stretched this to a much finer 100-point scale so that costs like "1 AP extra per tile for a raised weapon" become possible. The old 25-AP formula is still visible, commented out, right above the current one in the source.

The scale is set by the first key in the file:

[APConstants]
AP_MAXIMUM = 100

The file header spells out the contract: if you want a different AP system, change AP_MAXIMUM (valid range 25–250) and nothing else — every other AP value in the file must stay expressed on the 100-AP scale, and the game adjusts them dynamically. In the current source that is exactly what happens: at load time each value is multiplied by AP_MAXIMUM / 100 (the DynamicAdjustAPConstants() function in GameSettings.cpp). Set AP_MAXIMUM = 50 and a door that costs 12 AP to open on the 100 scale costs 6 in your game, automatically.

The only values exempt from this scaling are the five percentage factors near the top of the file (AP_YOUNG_MONST_FACTOR, AP_MONST_FRENZY_FACTOR, AP_CLAUSTROPHOBE, AP_AFRAID_OF_INSECTS, AP_WRONG_MAG). These are multipliers given in tenths — 9 means 90% of the calculated APs, 15 means 150% — so a claustrophobic merc underground operates at 90% APs, and reloading from a wrong-sized magazine costs 150% of the normal reload price.

How a merc's AP total is built

Knowing where the budget comes from helps when judging the costs below. From the current source (CalcActionPoints() in Soldier Control.cpp), on the 100-point scale:

  • Base points come from stats: 20 + (10 × level + 3 × agility + 2 × max health + 2 × dexterity) / 10, designed to give a default range of roughly 40–100.
  • Gear can add or remove APs (item AP bonuses and penalties).
  • Injury cuts the total by up to two thirds, low breath by up to half, and carrying more than 100% of your weight limit scales it down further.
  • The result is scaled to your AP_MAXIMUM, floored at AP_MINIMUM (default 40) and capped at the body-type maximum: AP_MAXIMUM for people, AP_MONSTER_MAXIMUM (160) for crepitus, AP_VEHICLE_MAXIMUM (200) for vehicles.
  • Multipliers then apply for phobias (the tenths factors above), young or frenzied monsters, and — with the new trait system — a bonus of +5% APs per Squadleader in the vicinity.

The same constants govern everyone: your mercs, militia, civilians and the queen's troops all shop from this price list (enemies can additionally receive a difficulty-dependent AP bonus). Cheapening an action for yourself cheapens it for the AI too.

Leftover APs, interrupts and going negative

Unspent APs are not wasted. At the start of a new turn a soldier keeps up to MAX_AP_CARRIED (default 20) of last turn's points and adds a freshly calculated total on top. Saved APs also make your mercs react faster and are required for interrupts at all — MIN_APS_TO_INTERRUPT (default 16) is the minimum a soldier must hold to get one. See interrupts for why ending a turn with spare APs is overwatch, not waste.

APs can also go negative: suppression fire and heavy hits push a soldier's AP count below zero, eating into the next turn. AP_MIN_LIMIT (default -100) is the absolute floor — with the default value a soldier can lose at most one full turn in advance.

Editing the file

This file is the combat balance

Weapon stats, terrain costs, interrupt behavior and the suppression system were all tuned against these defaults. Casual edits ripple much further than they look: halving movement costs makes rushing (by the AI too) dominant, cheap stance changes trivialize suppression, and a higher MAX_AP_CARRIED inflates interrupts and overwatch for both sides. The file's own comments carry the same warnings — AP_MAXIMUM "should be 5x MAX_AP_CARRIED for game-balance purposes", and MAX_AP_CARRIED "should be no more than 1/5 of AP_MAXIMUM, or game balance may be seriously disturbed." Back the file up, change one value at a time, and test.

Two practical notes:

  • Unlike Ja2_Options.INI, most keys in this file are read without range checking — only a few (such as AP_MAXIMUM, clamped to 25–250, and AP_MINIMUM, clamped to 10–100) fall back to sane values when out of range. A typo elsewhere is taken at face value. If you delete a line entirely, the built-in default is used.
  • Updates overwrite Data-1.13\APBPConstants.ini. To keep your tuning across updates, add the file to the MERGE_INI_FILES list in Ja2.ini and put your changed keys in a copy in your user profile folder — see keeping your changes across updates.

The headline constants

Key Default What it does
AP_MAXIMUM 100 The AP scale and the cap for human soldiers (range 25–250)
AP_MINIMUM 40 Floor for the freshly calculated APs a soldier gains each turn
MAX_AP_CARRIED 20 Unspent APs carried into the next turn (keep at 1/5 of maximum)
MIN_APS_TO_INTERRUPT 16 Minimum APs held to be eligible for an interrupt
AP_MONSTER_MAXIMUM 160 AP cap for crepitus
AP_VEHICLE_MAXIMUM 200 AP cap for vehicles
AP_MIN_LIMIT -100 How far below zero suppression and hits can push APs

Movement

Movement is priced per tile: the terrain cost plus a modifier for your movement mode. The terrain costs, from the file:

Terrain AP/tile Terrain AP/tile
Flat ground, roads 12 Shallow water (wading) 28
Grass 14 Deep water (swimming) 32
Bushes 18 Waist-deep water (wading) 36
Rubble 24

Swimming in deep water is deliberately cheaper than wading chest-deep — the source comments note a swimmer moves faster than a wader. The movement mode then adjusts the per-tile price:

Modifier Default Applies when
AP_MODIFIER_RUN -8 Running
AP_MODIFIER_WALK -4 Walking
AP_MODIFIER_SWAT 0 Moving stooped
AP_MODIFIER_CRAWL 4 Crawling prone
AP_MODIFIER_WEAPON_READY 1 Walking/sidestepping with the weapon raised
AP_MODIFIER_PACK 4 Cap on the extra per-tile cost from a worn backpack (1 AP per 5 kg of backpack weight, at most this value)
AP_REVERSE_MODIFIER 4 Moving backwards
AP_STEALTH_MODIFIER 8 Sneaking in stealth mode (reduced by the Stealthy trait)
AP_START_RUN_COST 4 One-time surcharge for breaking into a run

So a healthy merc running on flat ground pays 12 − 8 = 4 AP per tile — about 25 tiles on a full 100-AP turn — while sneaking through bushes costs 18 + 8 = 26 AP per tile. That gap is the tactical trade-off between speed and stealth; tune it with care.

Stances, turning and looking

Key Default What it does
AP_CROUCH 6 Going to or from a crouch
AP_PRONE 8 Going to or from prone (from crouch)
AP_CHANGE_FACING 4 Turning while standing
AP_CHANGE_TARGET 2 Switching to another target within your current facing
AP_LOOK_STANDING / _CROUCHED / _PRONE 4 / 6 / 8 Looking around (binoculars) per stance

Stance costs apply in each direction, and the source notes that turning while prone is really three actions — rise to crouch, turn, drop back down — so it charges AP_PRONE twice plus the turn.

Weapons and shooting

The cost of firing is mostly not in this file. Each gun's shot, burst and ready costs come from its entry in Weapons.xml (the file's own comments say the AP_READY_* and AP_RELOAD_GUN keys here are normally superseded by the weapon data), globally adjusted per weapon class by the modifiers in Item_Settings.ini. On top of that, attack costs scale with the shooter's own AP total, so a slow merc pays proportionally less per shot and everyone gets a broadly similar number of attacks per turn. What this file does control:

Key Default What it does
AP_CLICK_AIM 4 APs per extra aim click (iron sights)
AP_FIRST_CLICK_AIM_SCOPE … AP_EIGHTH_CLICK_AIM_SCOPE 4–11 Rising cost of each successive aim click through a scope
AUTOFIRE_SHOTS_AP_VALUE 20 How many APs the bAutofireShotsPerFiveAP weapon stat represents — "FiveAP" was right for the 25-AP system, 20 suits the 100-AP scale
AP_RELOAD_LOOSE 8 Reloading a single loose round (shotguns and the like)
AP_UNJAM 2 Clearing a jammed weapon
AP_CLEANINGKIT 80 Cleaning a fouled weapon with a cleaning kit mid-combat
AP_WRONG_MAG 15 Reload cost multiplier (150%) when using a wrong-sized magazine
AP_READY_DUAL 4 Readying two weapons at once
AP_GRENADE_MODE 4 Switching a launcher to grenade mode
AP_PUNCH 16 Throwing a punch
BAD_AP_COST 36 Shot cost at which the UI labels a gun "slow firing"
DEFAULT_APS / DEFAULT_AIMSKILL 80 / 80 Assumed AP pool and aim skill used to display AP costs in item infoboxes

Jamming, fouling, loose-round reloading and cleaning kits are explained on the weapon mechanics page.

Doors, locks and obstacles

The breaching price list — see explosives & breaching for the mechanics behind it:

Action Key AP
Open or close a door AP_OPEN_DOOR 12
Examine a lock AP_EXAMINE_DOOR 20
Unlock / lock with a key AP_UNLOCK_DOOR / AP_LOCK_DOOR 24
Kick a door AP_BOOT_DOOR 32
Pick a lock AP_PICKLOCK 40
Force with a crowbar AP_USE_CROWBAR 40
Blow the lock AP_EXPLODE_DOOR 40
Disarm a door trap AP_UNTRAP_DOOR 40
Cut a fence AP_USEWIRECUTTERS 40

Getting over and around things:

Action Key AP
Climb onto a roof / wall AP_CLIMBROOF / AP_JUMPWALL 40 / 40
Climb down from a roof / wall AP_CLIMBOFFROOF / AP_JUMPOFFWALL 24 / 40
Jump a fence (without / with backpack) AP_JUMPFENCE / AP_JUMPFENCEBPACK 24 / 40
Jump through a window AP_JUMPWINDOW 40
Jump over a prone merc AP_JUMP_OVER 20
Swap places with another character AP_EXCHANGE_PLACES 20

Items and inventory

Basic item handling: picking an item off the ground costs AP_PICKUP_ITEM = 12, handing one to an adjacent merc AP_GIVE_ITEM = 4, tossing one AP_TOSS_ITEM = 32, and stealing from an enemy AP_STEAL_ITEM = 32.

The AP_INV_FROM_* / AP_INV_TO_* block prices moving items between the slots of the new inventory system — grabbing something out of a vest pocket is quick, digging it out of a backpack is not:

Slot Take from Put into
Hands 0 0
Face (glasses etc.) 2 2
Rig 4 5
Vest 5 6
Knife sheath 5 6
Big / small pocket 5 / 4 4 / 5
Combat pack 6 7
Sling 6 7
Backpack 8 8
Worn equipment (armor, LBE) 15 20

AP_INV_MAX_COST = 25 caps the total for a single move. Related keys: AP_BACK_PACK = 12 for the backpack action itself and AP_OPEN_ZIPPER = 24 / AP_CLOSE_ZIPPER = 28 for opening and closing it. Whether shuffling items in the inventory screen costs APs at all is governed by INVENTORY_MANIPULATION_COSTS_AP (default FALSE) in [Tactical Interface Settings] of Ja2_Options.INI, with INV_AP_WEIGHT_DIVISOR adjusting the weight-based part of the calculation.

Field work: explosives, mines, fortifications

Action Key AP
Place a bomb AP_DROP_BOMB 12
Arm a bomb/grenade in inventory AP_INVENTORY_ARM 20
Flip a switch / handheld detonator AP_PULL_TRIGGER / AP_USE_REMOTE 8 / 8
Bury a mine AP_BURY_MINE 30
Disarm a mine or booby trap AP_DISARM_MINE 40
Rig a string-and-can alarm to a door AP_ATTACH_CAN 20
Build a fortification AP_FORTIFICATION 250
Tear down a fortification AP_REMOVE_FORTIFICATION 150

Fortification costs deliberately exceed a full turn's APs — building sandbags is a multi-turn undertaking; see fortifications.

Interactions and special actions

A curated selection from the long tail of the file:

Action Key AP
Talk to someone AP_TALK 24
Start first aid / start repairing AP_START_FIRST_AID / AP_START_REPAIR 20 / 20
Drink from canteen AP_DRINK 20
Eat (food system) AP_EAT 80
Apply camouflage AP_CAMOFLAGE 40
Put on a disguise (covert ops) AP_DISGUISE 80
Handcuff someone (prisoners) AP_HANDCUFF 50
Apply an item to someone else AP_APPLYITEM 50
Activate the spotter skill (support roles) AP_SPOTTER 20
Take a photo AP_CAMERA 30
Read a file AP_READFILE 50
Hack a computer AP_HACK 300
Fill a blood bag from a merc AP_FILLBLOODBAG 100
Refuel a vehicle AP_REFUEL_VEHICLE 40
Enemy soldier using his radio AP_RADIO 20

Suppression and taking hits

These keys shape how hard suppression fire and wounds bite:

Key Default What it does (per the file's comments)
AP_MAX_SUPPRESSED 64 Maximum AP penalty from a single suppressing attack
AP_MAX_TURN_SUPPRESSED 200 Maximum AP penalty from suppression in one turn
AP_SUPPRESSION_MOD 24 How effective each suppression point is
AP_LOST_PER_MORALE_DROP 12 How effective morale lost to suppression is
AP_GET_WOUNDED_DIVISOR 1 Divisor for APs lost per point of damage taken
AP_LOSS_PER_LEGSHOT_DAMAGE 4 Extra AP loss per point of leg damage
AP_FALL_DOWN 16 AP loss from falling down (marbles, hard hits)

Note that AP_MAX_TURN_SUPPRESSED (200) is twice the default AP maximum — combined with AP_MIN_LIMIT = -100, sustained fire can strip a soldier's whole turn and push him a full turn into debt.

Breath points

The [BPConstants] section prices the energy side of the same actions. It works in fine-grained breath points: BP_RATIO_RED_PTS_TO_NORMAL = 100 means 100 breath points equal one point of the 0–100 energy bar (a higher ratio means smaller energy changes per action). So BP_CLIMBROOF = 500 — climbing onto a roof — drains 5 energy, while BP_UNJAM = 10 is a barely measurable effort.

The keys that shape stamina gameplay:

  • Real-time modifiers: BP_RT_BREATH_RECOVER_MODIFIER = 100 and BP_RT_BREATH_DEDUCT_MODIFIER = 125 scale breath regeneration and movement drain in real-time mode (100 = 1×, up to 1000 = 10×). Raising the recovery modifier is the polite way to spend less time waiting for winded mercs outside combat.
  • Movement drain factors: BP_RUN_ENERGYCOSTFACTOR = 3, BP_WALK_ENERGYCOSTFACTOR = 1, BP_SWAT_ENERGYCOSTFACTOR = 2, BP_CRAWL_ENERGYCOSTFACTOR = 4 — running is three times as tiring as walking, crawling four times.
  • End-of-turn effort: the four BP_PER_AP_* values (from -50 for no effort to 6 for moderate effort) set the breath change per AP at the end of a turn; the negative values are recovery — a merc who spent the turn resting regains breath (rain reduces this gain). The file notes these are dynamically adjusted with AP_MAXIMUM, like the AP values.
  • Per-action costs mirror the AP tables: terrain (BP_MOVEMENT_FLAT = 5 up to BP_MOVEMENT_OCEAN = 100), stance changes (BP_CROUCH / BP_PRONE = 10), and the expensive physical feats — BP_USE_CROWBAR = 350, BP_BOOT_DOOR = 200, BP_JUMPFENCEBPACK = 500, BP_BURY_MINE = 250, BP_FORTIFICATION = 700. Getting hit costs BP_GET_HIT = 200, falling down BP_FALL_DOWN = 250.

This is why a night of crowbarring doors and hopping fences leaves a squad gasping: in energy-bar terms those actions cost 2–5 points each, on top of movement drain.

Sources