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Cataclysm: Bright Nights


Monster types

Monster types are specified as JSON object with “type” member set to “MONSTER”:

    "type": "MONSTER",
    "id": "mon_foo",

The id member should be the unique id of the type. It can be any string, by convention it has the prefix “mon_“. This id can be referred to in various places, like monster groups or in mapgen to spawn specific monsters.

For quantity strings (ie. volume, weight) use the largest unit you can keep full precision with.

Monster types support the following properties (mandatory, except if noted otherwise):


(string or object)

"name": "cow"
"name": { "ctxt": "fish", "str": "pike", "str_pl": "pikes" }

or, if the singular and plural forms are the same:

"name": { "ctxt": "fish", "str_sp": "bass" }

Name displayed in-game, and optionally the plural name and a translation context (ctxt).

If the plural name is not specified, it defaults to singular name + “s”.

Ctxt is used to help translators in case of homonyms (two different things with the same name). For example, pike the fish and pike the weapon.



In-game description for the monster.


(array of strings, optional)

Monster categories. Can be NULL, CLASSIC (only mobs found in classic zombie movies) or WILDLIFE (natural animals). If they are not CLASSIC or WILDLIFE, they will not spawn in classic mode. One can add or remove entries in mods via “add

” and “remove


(array of strings, optional)

A list of species ids. One can add or remove entries in mods via “add

” and “remove
”, see Modding below. Properties (currently only triggers) from species are added to the properties of each monster that belong to the species.




"volume": "40 L"

The numeric part of the string must be an integer. Accepts L, and ml as units. Note that l and mL are not currently accepted.



"weight": "3 kg"

The numeric part of the string must be an integer. Use the largest unit you can keep full precision with. For example: 3 kg, not 3000 g. Accepts g and kg as units.


(array of strings, optional)

List of scenttype_id tracked by this monster. scent_types are defined in scent_types.json


(array of strings, optional)

List of scenttype_id ignored by this monster. scent_types are defined in scent_types.json

“symbol”, “color”


Symbol and color representing monster in-game. The symbol must be a UTF-8 string, that is exactly one console cell width (may be several Unicode characters). See for details.


(string, optional)

Size flag, see


(array of strings, optional)

The materials the monster is primarily composed of. Must contain valid material ids. An empty array (which is the default) is also allowed, the monster is made of no specific material. One can add or remove entries in mods via “add

” and “remove


(string, optional)

It describes monster’s body state of matter. However, it doesn’t seem to have any gameplay purpose, right now. It can be SOLID, LIQUID, GAS, PLASMA or NULL.



The id of the faction the monster belongs to, this affects what other monsters it will fight. See Monster factions.



The id of the monster’s bodytype, which is a general description of the layout of the monster’s body.

Value should be one of:

angela winged human
beara four legged animal that can stand on its hind legs
birda two legged animal with two wings
bloba blob of material
craba multilegged animal with two large arms
quadrupeda four legged animal
elephanta very large quadruped animal with a large head and torso with equal sized limbs
fishan aquatic animal with a streamlined body and fins
flying insecta six legged animal with a head and two body segments and wings
froga four legged animal with a neck and with very large rear legs and small forelegs
gatora four legged animal with a very long body and short legs
humana bipedal animal with two arms
insecta six legged animal with a head and two body segments
kangarooa pentapedal animal that utilizes a large tail for stability with very large rear legs and smaller forearms
lizarda smaller form of ‘gator’
migowhatever form migos have
piga four legged animal with the head in the same line as the body
spideran eight legged animal with a small head on a large abdomen
snakean animal with a long body and no limbs


(integer, optional)

Number of moves per regular attack.


(integer, optional)

Monster baseline difficulty. Impacts the shade used to label the monster, and if it is above 30 a kill will be recorded in the memorial log. Monster difficult is calculated based on expected melee damage, dodge, armor, hit points, speed, morale, aggression, and vision ranges. The calculation does not handle ranged special attacks or unique special attacks very well, and baseline difficulty can be used to account for that. Suggested values:

2a limited defensive ability such as a skitterbot’s taser, or a weak special like a shrieker zombie’s special ability to alert nearby monsters, or a minor bonus to attack like poison or venom.
5a limited ranged attack weaker than spitter zombie’s spit, or a powerful defensive ability like a shocker zombie’s zapback or an acid zombie’s acid spray.
10a powerful ranged attack, like a spitters zombie’s spit or an turret’s 9mm SMG.
15a powerful ranged attack with additional hazards, like a corrosize zombie’s spit
20a very powerful ranged attack, like a laser turret or military turret’s 5.56mm rifle, or a powerful special ability, like a zombie necromancer’s ability to raise other zombies.
30a ranged attack that is deadly even for armored characters, like an anti-material turret’s .50 BMG rifle.

Most monsters should have difficulty 0 - even dangerous monsters like a zombie hulk or razorclaw alpha. Difficulty should only be used for exceptional, ranged, special attacks.


(integer, optional)

Defines how aggressive the monster is. Ranges from -99 (totally passive) to 100 (guaranteed hostility on detection)


(integer, optional)

Monster morale. Defines how low monster HP can get before it retreats. This number is treated as % of their max HP.



Monster speed. 100 is the normal speed for a human being - higher values are faster and lower values are slower.


(float, optional)

Used as the acceptable rider vs. mount weight percentage ratio. Defaults to “0.3”, which means the mount is capable of carrying riders weighing <= 30% of the mount’s weight.


(integer, optional)

Monster melee skill, ranges from 0 - 10, with 4 being an average mob. See GAME_BALANCE.txt for more examples


(integer, optional)

Monster dodge skill. See GAME_BALANCE.txt for an explanation of dodge mechanics.


(array of objects, optional)

List of damage instances added to die roll on monster melee attack. - damage_type valid entries are : “true”, “biological”, “bash”, “cut”, “acid”, “stab”, “heat”, “cold” and “electric”. - amount amount of damage. - armor_penetration how much of the armor the damage instance ignores. - armor_multiplier is a multiplier on armor_penetration. - damage_multiplier is a multiplier on amount.

"melee_damage": [ { "damage_type": "electric", "amount": 4.0, "armor_penetration": 1, "armor_multiplier": 1.2, "damage_multiplier": 1.4 } ],

“melee_dice”, “melee_dice_sides”

(integer, optional)

Number of dices and their sides that are rolled on monster melee attack. This defines the amount of bash damage.


(integer, optional)

Intensity of the grab effect applied by this monster. Defaults to 1, is only useful for monster with a GRAB special attack and the GRABS flag. A monster with grab_strength = n applies a grab as if it was n zombies. A player with max(Str,Dex)<=n has no chance of breaking that grab.


(integer, optional)

Amount of cutting damage added to die roll on monster melee attack.

“armor_bash”, “armor_cut”, “armor_stab”, “armor_acid”, “armor_fire”, “armor_cold”, “armor_electric”

(integer, optional)

Monster protection from bashing, cutting, stabbing, acid, fire, cold and electric damage.

“vision_day”, “vision_night”

(integer, optional)

Vision range in full daylight and in total darkness.


(integer, optional)

Amount of light passively output by monster. Ranges from 0 to 10.



Monster hit points.


(string or item group, optional)

An item group that is used to spawn items when the monster dies. This can be an inlined item group, see The default subtype is “distribution”.


(array of strings, optional)

How the monster behaves on death. See for a list of possible functions. One can add or remove entries in mods via “add

” and “remove


(string, optional)

If this monster’s death function leaves a corpse behind, this defines what items will be produced when butchering or dissecting its corpse. If none is specified, it will default to human. Harvest entries, their yields, and mass ratios, are defined in harvest.json


(array of objects of emit_id and time_duration, optional) “emit_fields”: [ { “emit_id”: “emit_gum_web”, “delay”: “30 m” } ],

What field the monster emits and how often it does so. Time duration can use strings: “1 h”, “60 m”, “3600 s” etc…


(integer, optional)

Number of hitpoints regenerated per turn.


( array of objects consisting of effect, base_mod (float) and scaling_mod (float), optional ) “regeneration_modifiers”: [ { “effect”: “on_fire”, “base_mod”: -0.3, “scaling_mod”: -0.15 } ],

What effects (if any) affect the monster’s regeneration positively/negatively. The mods stack additively (Intensity 2 on_fire produces a multiplier of 0.45) but are applied multiplicatively.


(boolean, optional)

Monster regenerates very quickly in poorly lit tiles.


(boolean, optional)

Will stop fleeing if at max hp, and regen anger and morale.


(array of special attack definitions, optional)

Monster’s special attacks. This should be an array, each element of it should be an object (new style) or an array (old style).

The old style array should contain 2 elements: the id of the attack (see for a list) and the cooldown for that attack. Example (grab attack every 10 turns):

"special_attacks": [ [ "GRAB", 10 ] ]

The new style object should contain at least a “type” member (string) and “cooldown” member (integer). It may contain additional members as required by the specific type. Possible types are listed below. Example:

"special_attacks": [
    { "type": "leap", "cooldown": 10, "max_range": 4 }

“special_attacks” may contain any mixture of old and new style entries:

"special_attacks": [
    [ "GRAB", 10 ],
    { "type": "leap", "cooldown": 10, "max_range": 4 }

One can add entries with “add

”, which takes the same content as the “special_attacks” member and remove entries with “remove
”, which requires an array of attack types. Example:

"remove:special_attacks": [ "GRAB" ],
"add:special_attacks": [ [ "SHRIEK", 20 ] ]


(array of strings, optional)

Monster flags. See for a full list. One can add or remove entries in mods via “add

” and “remove

“fear_triggers”, “anger_triggers”, “placate_triggers”

(array of strings, optional)

What makes the monster afraid / angry / what calms it. See for a full list


(string, optional)

If not empty and a valid item id, the monster can be converted into this item by the player, when it’s friendly. This is usually used for turrets and similar to revert the turret monster back into the turret item, which can be picked up and placed elsewhere.


(object, optional)

An object containing ammo that newly spawned monsters start with. This is useful for a monster that has a special attack that consumes ammo. Example:

"starting_ammo": { "9mm": 100, "40mm_frag": 100 }


(boolean or object, optional)

Controls how this monster is upgraded over time. It can either be the single value false (which is the default and disables upgrading) or an object describing the upgrades.


"upgrades": {
    "into_group": "GROUP_ZOMBIE_UPGRADE",
    "half_life": 28

The upgrades object may have the following members:


(int) Time in which half of the monsters upgrade according to an approximated exponential progression. It is scaled with the evolution scaling factor which defaults to 4 days.


(string, optional) The upgraded monster’s type is taken from the specified group. The cost in these groups is for an upgrade in the spawn process (related to the rare “replace_monster_group” and “new_monster_group_id” attributes of spawning groups).


(string, optional) The upgraded monster’s type.


(int, optional) Number of days needed for monster to change into another monster.


(dictionary, optional) The monster’s reproduction cycle, if any. Supports:


(string, optional) the id of the monster spawned on reproduction for monsters who give live births. You must declare either this or baby_egg for reproduction to work.


(string, optional) The id of the egg type to spawn for egg-laying monsters. You must declare either this or “baby_monster” for reproduction to work.


(int) Number of new creatures or eggs to spawn on reproduction.


(int) Number of days between reproduction events.


(Array, optional) Designate seasons during which this monster is capable of reproduction. ie: [ "SPRING", "SUMMER" ]


(array, optional)

A special defense attack, triggered when the monster is attacked. It should contain an array with the id of the defense (see Monster defense attacks in and the chance for that defense to be actually triggered. Example:

"special_when_hit": [ "ZAPBACK", 100 ]


(array of objects, optional)

A set of effects that may get applied to the attacked creature when the monster successfully attacks. Example:

"attack_effs": [
        "id": "paralyzepoison",
        "duration": 33,
        "chance": 50

Each element of the array should be an object containing the following members:



The id of the effect that is to be applied.


(integer, optional)

How long (in turns) the effect should last.


(boolean, optional)

Whether the effect should be applied to the hit body part instead of the one set below.


(string, optional)

The body part that where the effect is applied. The default is to apply the effect to the whole body. Note that some effects may require a specific body part (e.g. “hot”) and others may require the whole body (e.g. “meth”).


(integer, optional)

The chance of the effect getting applied.


Monster types can be overridden or modified in mods. To do so, one has to add an “edit-mode” member, which can contain either:

  • “create” (the default if the member does not exist), an error will be shown if a type with the given id already exists.
  • “override”, an existing type (if any) with the given id will be removed and the new data will be loaded as a completely new type.
  • “modify”, an existing type will be modified. If there is no type with the given id, an error will be shown.

Mandatory properties (all that are not marked as optional) are only required if edit mode is “create” or “override”.

Example (rename the zombie monster, leaves all other properties untouched):

  "type": "MONSTER",
  "edit-mode": "modify",
  "id": "mon_zombie",
  "name": "clown"

The default edit mode (“create”) is suitable for new types, if their id conflicts with the types from other mods or from the core data, an error will be shown. The edit mode “override” is suitable for re-defining a type from scratch, it ensures that all mandatory members are listed and leaves no traces of the previous definitions. Edit mode “modify” is for small changes, like adding a flag or removing a special attack.

Modifying a type overrides the properties with the new values, this example sets the special attacks to contain only the “SHRIEK” attack:

  "type": "MONSTER",
  "edit-mode": "modify",
  "id": "mon_zombie",
  "special_attacks": [["SHRIEK", 20]]

Some properties allow adding and removing entries, as documented above, usually via members with the “add:”/“remove:” prefix.

Monster special attack types

The listed attack types can be as monster special attacks (see “special_attacks”).


Makes the monster leap a few tiles. It supports the following additional properties:


(Required) Maximal range of attack.


(Required) Minimal range needed for attack.


This prevents monster from using the ability on empty space.


Turns needed to complete special attack. 100 move_cost with 100 speed is equal to 1 second/turn.

“min_consider_range”, “max_consider_range”

Minimal range and maximal range to consider for using specific attack.


Makes monster use teeth to bite opponent. Some monsters can give infection by doing so.


Max damage it can deal on one bite.

“min_mul”, “max_mul”

How hard is to get free of bite without killing attacker.


Turns needed to complete special attack. 100 move_cost with 100 speed is equal to 1 second/turn.


(Integer) How accurate it is. Not many monsters use it though.


Chance to not give infection.


Fires a gun at a target. If friendly, will avoid harming the player.


(Required) Valid item id of a gun that will be used to perform the attack.


(Required) Valid item id of the ammo the gun will be loaded with. Monster should also have a “starting_ammo” field with this ammo. For example

"ammo_type" : "50bmg",
"starting_ammo" : {"50bmg":100}


Cap on ammo. If ammo goes above this value for any reason, a debug message will be printed.


Strength stat of the fake NPC that will execute the attack. 8 if not specified.


Dexterity stat of the fake NPC that will execute the attack. 8 if not specified.


Intelligence stat of the fake NPC that will execute the attack. 8 if not specified.


Perception stat of the fake NPC that will execute the attack. 8 if not specified.


Array of 2 element arrays of skill id and skill level pairs.


Move cost of executing the attack

// If true, gives “grace period” to player


If true, the monster will need to “target” the player, wasting targeting_cost moves, putting the attack on cooldown and making warning sounds, unless it attacked something that needs to be targeted recently.


As above, but with npcs.


As above, but with monsters.


Targeting status will be applied for this many turns. Note that targeting applies to turret, not targets.


Successfully attacking will extend the targeting for this many turns. Can be negative.


Move cost of targeting the player. Only applied if attacking the player and didn’t target player within last 5 turns.


If true then attacking create will be unable to score ranged critical hit on target, also good hits no longer has high change to go to the head, instead there is high change to score hit to the body and limbs. If false then default behavior used - critical hits are allowed and good hit has high chance to reach head.


If true and attacking a creature that isn’t laser-locked but needs to be targeted, the monster will act as if it had no targeting status (and waste time targeting), the target will become laser-locked, and if the target is the player, it will cause a warning.

Laser-locking affects the target, but isn’t tied to specific attacker.


Maximum range at which targets will be acquired.


Maximum range at which targets will be attacked with a burst (if applicable).


Limit on burst size.


Description of the attack being executed if seen by the player.


Description of the sound made when targeting.


Volume of the sound made when targeting.


Description of the sound made when out of ammo.