Mossling

Based on game build 714014 | Last updated: 2026-03-06

Overview

The mossling prefab defines a seasonal creature that appears during spring and summer (and summer in the Caves). It is part of a herd (Moose egg herd), uses herd-based AI via herdmember, and engages in combat when attacked. The entity has a built-in lifecycle tied to seasonal changes—when spring ends or it enters the Caves, it marks itself for removal. It supports networked persistence via custom save/load handlers and integrates with DST’s combat, health, sound, and anim systems.

Usage example

The Mossling prefab is not typically instantiated manually; it is spawned by world generation (e.g., during Moose egg hatching). A modder might reference its components like so:

-- Example: checking if a Mossling is currently under a guardian's protection
if inst.components.herdmember.herd ~= nil then
    local has_guardian = inst.components.herdmember.herd.components.guardian:HasGuardian()
end

-- Example: modifying Mossling walk speed dynamically
inst.components.locomotor.walkspeed = TUNING.MOSSLING_WALK_SPEED * 1.5

Dependencies & tags

Components used: health, combat, sizetweener, sleeper, lootdropper, inspectable, knownlocations, inventory, herdmember, eater, burnable, locomotor.
Tags added: mossling, animal, herdmember.
Tags checked: prey, smallcreature, monster, player, moose (via RETARGET_CANT_TAGS, RETARGET_ONEOF_TAGS in RetargetFn).

Properties

Property	Type	Default Value	Description
mother_dead	boolean	false	Tracks whether the Mossling’s mother (e.g., the spawning entity) is dead; affects retargeting logic.
shouldGoAway	boolean	false	Set to true when season changes or in caves; triggers removal during sleep.

Main functions

HasGuardian(inst)

• Description: Helper function that returns true if the Mossling belongs to a herd with an active guardian. Used to conditionally adjust behavior (e.g., target retention).
• Parameters: inst (Entity) — the Mossling instance.
• Returns: boolean — true if the herd has a guardian, otherwise false.

RetargetFn(inst)

• Description: Entity-targeting function for the combat component. Determines whether the Mossling can find a valid new target. Only activates if mother_dead is true or the Mossling is no longer under a guardian’s protection. Uses FindEntity to locate a nearby valid target.
• Parameters: inst (Entity) — the Mossling instance.
• Returns: Entity? — the first valid target found, or nil.
• Error states: Returns nil if no valid target exists within range (TARGET_DIST = 6), or if all candidate entities are tagged with forbidden tags (prey, smallcreature, mossling, moose) or do not match required tags (monster, player).

KeepTargetFn(inst, target)

• Description: Validation function for retaining an existing target. Allows target retention unless the Mossling is under a guardian and the target is very close (within LOSE_TARGET_DIST = 13), in which case it drops the target.
• Parameters:
  • inst (Entity) — the Mossling instance.
  • target (Entity) — the candidate target.
• Returns: boolean — true if the target should be kept, otherwise false.

OnAttacked(inst, data)

• Description: Event handler for the attacked event. Assigns the attacker as the current target and attempts to share the target with up to 60 allies (other Mosslings or the guardian).
• Parameters:
  • inst (Entity) — the Mossling instance.
  • data (table) — event payload, must include attacker (Entity).
• Returns: Nothing.
• Note: Calls combat:SetTarget(data.attacker) and combat:ShareTarget(...) with a custom filter function that includes other Mosslings and the herd guardian.

OnSave(inst, data)

• Description: Saves persistent state before the game is closed. Stores mother_dead and shouldGoAway flags.
• Parameters:
  • inst (Entity) — the Mossling instance.
  • data (table) — the save table to populate.
• Returns: Nothing.

OnLoad(inst, data)

• Description: Restores state after loading. Applies previously saved mother_dead and shouldGoAway flags if present.
• Parameters:
  • inst (Entity) — the Mossling instance.
  • data (table) — the loaded save data.
• Returns: Nothing.

OnEntitySleep(inst)

• Description: Handles removal of the Mossling during sleep when shouldGoAway is true. Called automatically by the game state graph during the sleep transition.
• Parameters: inst (Entity) — the Mossling instance.
• Returns: Nothing.
• Note: Calls inst:Remove() if inst.shouldGoAway is true.

OnSpringChange(inst, isspring)

• Description: Reacts to seasonal changes (spring/summer flag). Sets shouldGoAway = true if it is not spring/summer or if the world has the "cave" tag. Triggers immediate removal if the entity is already sleeping.
• Parameters:
  • inst (Entity) — the Mossling instance.
  • isspring (boolean) — whether the current season is spring/summer.
• Returns: Nothing.

Events & listeners

• Listens to:
  • attacked — triggers OnAttacked to set or share targets.
  • entitysleep — triggers OnEntitySleep to remove the entity if shouldGoAway.
• Pushes: None (uses standard game events for save/load, health, and combat).