Explosives & breaching¶

Sooner or later a door, a fence or an entire building stands between your squad and the objective. This page covers every way through: picking and forcing locks, keys, door traps, smashing windows, blowing holes in walls, and using demolitions offensively. Placing mines and tripwire networks to keep the enemy out is the other side of the coin — see Fortifications.

Everything below describes the current GitHub releases and was verified against the 1.13 source and the stock Data-1.13 game data. Most of the numbers quoted come from Skills_Settings.INI and APBPConstants.ini and can be modded — see Configuration.

When a merc tries to open a locked door, a pop-up menu appears instead (unlocked doors simply open). The options are:

Option	What it does
Open Manually	Just try the handle (also how you trigger a known trap on purpose — don't).
Examine for Traps	Careful inspection for door traps.
Lockpick	Pick the lock. Needs a locksmith kit. Silent.
Force Open	Kick the door. Strength-based, noisy.
Use Crowbar	Pry the lock open. Needs a crowbar. Strength-based, noisy.
Use Door Explosive	Blow the lock off. Needs a Shaped Charge. Very noisy.
Untrap	Attempt to disarm a discovered trap.
Unlock / Lock	Use the matching key from your key ring or inventory.

Opening the menu already gives the merc a free, passive chance to spot a trap on the door; a merc who notices one says so out loud.

Approximate costs on 1.13's 100-AP scale (from APBPConstants.ini, editable): opening a door 12 AP, examining for traps 20, kicking 32, and picking, prying, blowing the lock or untrapping 40 each. Mercs with the Ambidextrous trait handle doors (and bombs) 33% faster — see Skills & traits.

Every locked door references a lock type (loaded from BINARYDATA\Locks.bin, part of the base game data) with two separate difficulty numbers: a pick difficulty and a smash difficulty. Either can be flagged as flat-out impossible — some locks can never be picked, some can never be forced, and a few quest doors can't be opened by force at all.

Lockpicking¶

Lockpicking requires a locksmith kit somewhere in the merc's inventory. The stock Locksmith Kit is the real tool; a Utility Knife also works as an improvised pick at a −10 penalty. The kit's condition matters: the final skill is scaled by the item's status percentage, so a battered 40% kit is less than half as useful.

The chance to pick a lock is built from (see SkillCheck in Tactical/SkillCheck.cpp):

Mechanical skill is the base — a merc with 0 Mechanical can never pick a lock.
Scaled by Wisdom and Dexterity (each maps 0–100 to a ×0.5–×1.0 factor).
Plus 3 points per experience level.
Under the new trait system, everyone takes a flat −10 penalty (LOCKPICKING_CHECK_MODIFIER), and electronic and card locks halve the skill. The Technician trait then adds a flat +30 per trait level (LOCKPICKING_BONUS) — an Engineer (Technician ×2) gets +60, which also applies to electronic locks.
The lock's pick difficulty is subtracted; fatigue, low morale, and some character quirks (Aggressive −10, Phlegmatic +5 on all patience checks) shift the chance.
If the resulting chance is below 15%, it becomes 0 — the merc simply is not good enough for this lock and will eventually say so.

Successful picking trains Mechanical, Dexterity and Wisdom. Failing costs nothing but time — you can keep trying. Lockpicking is the only silent way through a locked door, which makes a good picker essential for stealth play.

Keys and the key ring¶

If you find or loot the matching key, none of the above matters: Unlock works instantly for 24 AP. A key is usable from the merc's key ring or regular inventory. Press K with the inventory panel open to see a merc's key ring (see Hotkeys); 1.13 raised the ring's capacity from 64 to 255 keys. Keys can also lock doors behind you — useful when retreating.

With the enemy-roles feature enabled, observing enemies long enough reveals which soldier is carrying a key (a small icon appears next to them) — killing and searching that one soldier can open a whole compound. See Know your enemy.

Forcing doors: boots and crowbars¶

Both brute-force options check Strength against the lock's smash difficulty:

Force Open (kick): raw Strength. With the new trait system, Martial Arts adds +25 per trait level (CHANCE_KICK_DOORS_BONUS) — a black belt is a door-opening machine.
Use Crowbar: Strength plus the tool's CrowbarModifier (0 for the standard crowbar — the item's job is enabling the attempt). Any item flagged as a crowbar works; in the stock data that is the Crowbar and, amusingly, the Rambo Knife. The crowbar loses a little condition with each attempt.

Failures are not wasted: a near-miss shows "Lock hit" and permanently damages the lock, lowering the effective smash difficulty for every later attempt (by any method). Success breaks the lock forever — the door can never be locked again — and awards Strength experience. Both methods generate serious noise, so expect visitors.

Rotate your kickers

Failed attempts still grant a token point of Strength practice now and then, and smashing checks are reduced by fatigue. If the first merc bounces off, let a stronger (or fresher) one take over — the accumulated lock damage carries over.

Blowing the lock: shaped charges¶

Use Door Explosive consumes one Shaped Charge (the only stock item flagged as a lock bomb) and rolls an explosives skill check:

On anything but a bad failure, the charge detonates on the lock. Its 60 damage is applied to the lock — tripled if the merc has the Demolitions trait (SHAPED_CHARGE_DAMAGE_MULTIPLIER = 3). If the (accumulated) damage beats the lock's smash difficulty, the lock is destroyed for good.
On a bad failure the charge goes off at the merc's feet.

Quite a few backgrounds change the odds via the <breachingcharge> tag in TableData\Backgrounds.xml — for example Gadget Master +50 and Veteran Sapper +40 (see IMP creation for backgrounds in general).

Door traps¶

Locked doors can be booby-trapped. The trap types (from Tactical/Keys.cpp):

Trap	Effect when triggered
Explosion	A hand-grenade-strength blast on the merc's own tile.
Electric	10–19 damage plus breath damage to the merc.
Super electric	20–39 damage plus heavier breath damage.
Siren	Klaxon sounds and all available enemies converge on the door.
Silent alarm	Same convergence, but you get no warning sound.
Brothel siren	Special variant in San Mona; summons Kingpin's men.

Detecting traps. A merc's trap-detection level is roughly: experience level, +1 per 40 Explosives, −1 per 20 missing Wisdom; Technicians get +2 per trait level. A passive check runs whenever a merc starts fiddling with a trapped locked door — if the detection level is below the trap's level, the trap goes off. Examine for Traps adds a random bonus on top, so deliberate examination is much safer than blundering in. Beware: a failed examination confidently reports the door as untrapped, and Optimist mercs are terrible at noticing traps.

Disarming. Once a trap is known, Untrap rolls a disarm check against the trap's level. Explosion traps use the explosives-based check (impossible without both Explosives and Mechanical skill under the new traits; the Demolitions trait adds +50). Electric/alarm traps use the electronics-based check (skill reduced by 25% for everyone; Technician adds +40 per trait level). Success removes the trap and trains Explosives or Mechanical, Dexterity and Wisdom. Failure sets the trap off.

Windows¶

Windows are the quick-and-dirty breach: smash the glass with \ (works with a crowbar or any two-handed weapon) and jump through with Shift+J — the merc must face the window and have a free landing tile on the other side. You can even jump through unbroken windows, taking minor cuts on the way (both behaviors are on by default via CAN_JUMP_THROUGH_WINDOWS and CAN_JUMP_THROUGH_CLOSED_WINDOWS in Ja2_Options.INI). Breaking glass is noisy, and enemies (and zombies, if enabled) can jump through windows too. See Hotkeys for the full movement key list.

Wire fences are a similar story: any item flagged as wire cutters — the stock Wire Cutters, KCB Knife or Hedge Trimmer — lets a merc cut through a fence section (40 AP plus the cost of crouching) instead of looking for the gate.

Breaching walls¶

Walls, like almost everything else in JA2, are destructible structures with a material-based armour value and hit points. The important mechanics (from TileEngine/structure.cpp and TileEngine/Explosion Control.cpp):

Only explosions damage normal structures. Regular gunfire never chips walls or doors down (special cases below).
Against explosions a structure only counts half its material armour (a third for explosive containers like fuel barrels). Whatever damage exceeds that armour is subtracted from the structure's hit points; run out and the wall section is gone.
Material armour in the source ranges from ~20–30 for wooden walls through 55 for stone masonry to 63–70 for concrete. Reinforced concrete survives anything but repeated heavy charges, and some map structures are flagged indestructible.
Placed charges apply their full blast damage to structures on their own tile (with wall checks on the neighbouring tiles, since a wall graphically "belongs" to the tile edge). Grenades only apply one third of their damage to structures — they are anti-personnel weapons, not breaching tools.
Big explosions also collapse roof sections above and around the blast, and destroying a container-like structure reveals the items that were inside.

The stock demolition blocks, from weakest to strongest (Explosives.xml damage / blast radius): RDX 40/5, TNT 50/5, C1 55/6, HMX 60/6, C4 65/7. Place the charge on the tile directly adjacent to the wall you want gone. One block of TNT reliably opens a wooden wall; masonry and concrete want C4, HMX, or several charges. A global tuning knob exists in Ja2_Options.INI: EXPLOSIVES_DAMAGE_MODIFIER (percentage, default 100).

Two exceptions to the "bullets don't breach" rule:

Anti-materiel ammo (the "SAP, anti-material" ammo type for heavy rifles) can damage and eventually destroy weaker structures — see Weapon mechanics for ammo types.
Ramming things with vehicles/tanks flattens lighter structures.

And the reverse case: tank armour can only be hurt by explosives and special ammo, so keep LAWs, RPGs or demolition charges at hand — see Enemies.

Timed and remote charges¶

A bare block of TNT/C4 does nothing until you give it a firing device as an attachment (see attachments for the interface):

Device	Behavior
Detonator	Timer. When planting you set the delay in turns ("How many turns 'til she blows").
Remote Detonator	Fires when you squeeze a Remote Bomb Trigger set to the same detonation frequency (1–4).
Remote Defuse	Lets you disarm your planted bomb remotely on a defuse frequency (A–D).
Remote Combo	Both of the above in one device.

Attaching a detonator is itself an explosives skill check (−15 base for the untrained; remote detonators halve the skill; the Demolitions trait adds +50). Planting the armed bomb is another check (remote bombs are 25% harder; Demolitions adds +50 again) — succeed and the bomb is buried with a concealment ("trap") level of Explosives/20 + level/3, capped at 10. Demolitions adds +5 to that level and raises the cap to 13, making your bombs much harder for enemies to spot, and some backgrounds add another +1. Fail badly and the bomb detonates in your hands. Demolitions experts also inflict +25% damage with all placed bombs and mines.

To keep track of what you buried where, use the mines display keys (Alt+End and friends — see Hotkeys). Disarming enemy devices, tripwire networks and the whole defensive minefield toolbox are covered in Fortifications.

Offensive demolitions: grenades and mortars¶

The full grenade family, briefly (delivery first, payload second):

Delivery: thrown hand grenades, under-barrel and stand-alone 40mm grenade launchers, rifle grenades, and mortars. Launchers can toggle high-angle fire with Ctrl+Q to lob shells farther (see Hotkeys). The Heavy Weapons trait boosts launcher accuracy and mortar handling, and the Throwing trait improves thrown grenades — numbers in Skills & traits.
Payloads: blast/fragmentation, stun, flashbang, tear gas, mustard gas, smoke and signal smoke. Gas and smoke behavior (spread, drift, gas masks) lives in Weather & environment.
Fragmentation is a 1.13 addition: frag grenades, 40mm HE and mortar shells release a cloud of fragments (e.g. 20 for a Mk2, 150 for a mortar shell, per Explosives.xml) that fly like tiny bullets and can wound targets well outside the blast radius.
Explosions also suppress everyone near the blast — often more valuable than the damage itself. See Suppression.

Mortars deserve their own mention: enemy mortarmen will happily use them on you (Enemies), and your radio operator can call mortar barrages from adjacent sectors (Support roles).

Safety notes¶

Explosives do not check IFF

Blast damage falls off linearly to the edge of the radius, but fragments, collapsing roofs and explosive suppression all reach beyond it. Keep friendlies at least a couple of tiles past the listed radius, behind hard cover, or prone.

Traps trigger on the victim's tile. The merc doing the breaching eats the explosion; don't stack the squad in the doorway behind them.
Gas lingers and drifts with the wind. Never pop mustard gas upwind of your own approach, and hand out gas masks before opening suspicious doors — see Weather & environment.
Grenades strapped to your vest can cook off. With ALLOW_EXPLOSIVE_ATTACHMENTS = TRUE in Ja2_Options.INI, volatile grenades/explosives attached to items can detonate; the companion setting ALLOW_SPECIAL_EXPLOSIVE_ATTACHMENTS enables improvised gas-can/marble/alcohol effects. Both default to FALSE.
DELAYED_GRENADE_EXPLOSION = TRUE makes hand and launcher grenades of the blast/stun/flashbang types (those without an explode-on-impact tag) detonate on the next turn instead of instantly — enough time to dive away, for both sides. Default FALSE.
Cosmetic-but-tactical: ADD_SMOKE_AFTER_EXPLOSION and ADD_LIGHT_AFTER_EXPLOSION (both default TRUE in the stock INI) make outdoor blasts leave brief smoke and a light flash — the smoke can block line of sight for a moment. See the options tour.

Sources¶

1dot13/source: Tactical/SkillCheck.cpp (lockpicking, detonator, planting, disarm and crowbar/kick checks; CalcTrapDetectLevel), Tactical/Keys.cpp and Keys.h (crowbar/smash/pick/untrap/ blow-up-lock logic, key ring capacity, trap effects, Locks.bin loading), Tactical/Handle Doors.cpp (door menu flow, passive trap check), Tactical/Handle Items.cpp (bomb planting, trap level, detonation on failure), Tactical/Items.cpp (crowbar/locksmith kit/lock bomb lookup), Tactical/Points.cpp (door/fence AP formulas), TileEngine/structure.cpp (material armour, structure damage), TileEngine/Explosion Control.cpp (blast falloff, structure/roof damage), Tactical/LOS.cpp (anti-materiel bullets), i18n/_EnglishText.cpp (door menu and bomb dialog strings)
1dot13/gamedir, current Data-1.13: Skills_Settings.INI ([Technician], [Demolitions], [Martial Arts], [Ambidextrous], [Heavy Weapons], [Throwing] and the generic check modifiers), APBPConstants.ini (door action AP costs), Ja2_Options.INI (explosive attachment, smoke/light, damage modifier settings), TableData/Items/Items.xml, TableData/Items/Explosives.xml, TableData/Items/AmmoTypes.xml, TableData/Backgrounds.xml