How does a monster notice your settlers, and what can you do about it? This page is read straight from the game's tables (DS_B.0.3.26) and the code dump; each number names the constant it comes from, and anything the data cannot confirm is flagged as such. Try the interactive detection-range calculator to plug in a specific monster.
The detection model what actually happens
Detection is vision-based and grid-based. Every unit - your settlers and every monster alike - carries a Vision Range stat that defines the set of floor tiles it can currently see, with walls blocking the view. When a monster's visible tiles include one of your units it starts to notice, and after a short awareness build-up it commits to the attack. There is no separate hearing or noise sense in the code.
A monster runs through three combat states (from the dump's
CombatState enum, driven every time a unit moves by MoveApplier.RefreshUnitCombatState):
- Unawared - idle or patrolling; it has not seen you.
- Awaring - one of your units has entered its sight; awareness is building.
- In Combat - awareness has hit the threshold; it locks on and engages.
The wake-up is not instant. While a player unit stays in a monster's sight,
the monster builds Awareness at 1 per in-game minute
(GAMESYSTEM_Combat_Basic_AwarenessOnMin, enemies only) and enters combat once it reaches
5 (GAMESYSTEM_Combat_Basic_AwarenessToCombat) - about
5 in-game minutes of unbroken sight, only ~4 seconds of real time at
1x speed. Cross a monster's view briefly and you can often clear it before it commits; attacking one, of course,
drops it straight into combat.
The custom AI is built on Behavior Designer
trees whose distance/vision checks (CheckEnemyDistance, CheckCombatTargetInRange)
read the same grid vision and aggro data - not 3D cone-of-vision raycasts. Whether Awareness decays when you
break line of sight is not spelled out in the data (inferred to reset or fall off, not confirmed).
Vision Range the spotting radius
Vision Range is the core number. The game's own description:
“The range in which the unit reveals nearby areas and can spot enemies.” It does double duty - it reveals fog of war for your side and it is the radius a
monster uses to spot you. It is measured in tiles and traced with line-of-sight, so a wall between
you and a monster blocks it (VisionDataHandler.IsPathVisible).
| Vision Range | Units | Examples |
|---|---|---|
| 4 | 2 | Gloth Pup, Gloth Pup nearsighted |
| 5 | 7 | FireDragonClawWarrior, HedgeHog, Heosuabi |
| 8 | 95 | Acid Insect, Acid Slogel, Bee standard |
| 12 | 2 | AlphaAcidSlogel, Alpha Acid Slogel farthest sight |
Values are the authored per-unit numbers in
UnitTable. Most units see 8 tiles; the AlphaAcidSlogel sees a long 12,
while a Gloth Pup is nearsighted at 4. Player-side units default to 7
(StatusValueTable); the growth system's fallback base is 5
(GAMESYSTEM_Unit_Growth_..._VisionRange).
Aggro and threat engaging, and who gets hit
Two separate constants govern the fight once you are seen:
- Aggro Range = 8 tiles (
GAMESYSTEM_Combat_Basic_AggroRange) - the threat radius a monster engages within. Because it equals the standard 8-tile sight, most monsters spot and commit to you at the same distance. - Aggro Correction = [1.3, 1]
(
GAMESYSTEM_Combat_Basic_AggroCorrection) - a per-attack-type multiplier on the aggro/threat a unit generates: melee x1.3, ranged x1. A melee attacker draws about 30% more aggro than a ranged one, so front-liners naturally pull the monster's attention off your casters. This steers target selection, not whether you are first noticed.
The dump confirms the constants and the melee/ranged split (dev comment: [0] melee, [1] ranged) but the method bodies are stripped, so the exact arithmetic that applies the multiplier is inferred, not read line-by-line. No leash or return-to-spawn timer was found in the code - a monster that reaches Unawared again simply drops its target.
Day and night sight shrinks after dark
The dungeon runs on a day/night clock. Daytime is 06:00 to 20:00
(GAMESYSTEM_Campaign_DayTimes); outside that window it is night.
At night, vision is reduced by 3 tiles
(GAMESYSTEM_Campaign_DayNightVisionDiffrence). A standard 8-tile monster effectively sees only
5 at night - but the same penalty clips your own units' sight, so a night raid cuts
both ways. The Night Vision affecter adds +3 Vision Range,
precisely undoing the night penalty for whoever carries it.
Whether the night penalty is applied to
monsters, to the player, or to both is not fully pinned down in the metadata dump - the per-unit
Status_VisionRange class does carry an IsPlayer flag, which hints the two sides can
be treated differently, but that is an inference, not a confirmed rule.
Stealth the clean escape hatch
Stealth is the one hard counter to detection. The in-game text: “Remain undetected and untargetable. This effect ends immediately if you deal damage to an enemy.”
It is a code flag (it adjusts no stat), so it is all-or-nothing: while active you cannot be seen or targeted, regardless of Vision Range or distance. The catch is spelled out in the description - it ends the instant you deal damage, so it is a repositioning and scouting tool, not a way to fight unseen. Sources: Stealth Potion and Stealth Potion.
The Perception myth name vs. effect
It is natural to assume the Perception stat sharpens how far your units see - the name and flavour ("sharpens senses") both suggest it. The data does not back that up.
In this build Perception's StatusValueTable coefficient for Vision Range is
0, and the stat's own tooltip lists only Physical Attack, Magic Attack, Critical Chance and Cooking.
A dormant growth constant (...MajorStatToFinalStatFactor_VisionRange = 0.02) does
tie Perception to sight at 0.02 per point, but with the live coefficient at 0 it appears
inactive. So the Perception Fortify / Perception Weaken
environment conditions (±30% Perception) and the +3 Perception Elixir are
best read as combat buffs, not detection modifiers. Treat any "Perception widens vision" claim as
unconfirmed.
What raises or lowers detection the summary
Everything above in one table. "Effect" is from the monster's point of view - how easily it picks you up.
| Factor | Effect | What the data shows |
|---|---|---|
| Monster's Vision Range | varies | Each unit carries its own sight radius (UnitTable.VisionRange): from 4 (Gloth Pup) up to 12 (AlphaAcidSlogel), most sit at 8. Bigger radius = it spots you from farther off. |
| Line of sight (walls) | lowers | Sight is traced tile by tile and blocked by walls and obstacles (VisionDataHandler.IsPathVisible). Breaking line of sight around a corner hides you even at point-blank range. |
| Night | both sides -3 | From 20:00 to 06:00 vision drops by 3 tiles (DayNightVisionDiffrence). This shortens a monster's reach, but it clips your own scouts' sight too. |
| Night Vision (affecter) | restores +3 | Adds +3 Vision Range (Night Vision), exactly cancelling the night penalty. Defined in the data but not currently granted by any obtainable item or skill. |
| Stealth (potion / skill) | hidden | Stealth: “Remain undetected and untargetable. This effect ends immediately if you deal damage to an enemy.” A hard on/off flag, granted by Stealth Potion and Stealth Potion. |
| Aggro Range | 8 tiles | The threat radius a monster engages within (GAMESYSTEM_Combat_Basic_AggroRange = 8). It matches the standard 8-tile sight, so for most monsters spotting and engaging happen at the same distance. |
| Attack type (melee vs ranged) | targeting | Aggro/threat is scaled by how you hit: melee x1.3, ranged x1 (AggroCorrection). Melee draws 30% more aggro, so it steers which of your units a monster fixates on - a tanking lever, not initial spotting. |
| Perception (Fortify / Weaken / Elixir) | unclear | Despite the name, the Perception stat governs Physical & Magic Attack, Critical Chance and Cooking - its live StatusValueTable Vision Range coefficient is 0 and the in-game tooltip lists no sight effect. So Perception Fortify / Perception Weaken (±30%) and the +3 Perception Elixir are not confirmed detection modifiers in this build. |
Playing around it practical read
- Corners beat distance. Line of sight is the only hard, always-on limiter. A wall hides you at any range; open ground does not, even far away.
- Scout the outliers. A AlphaAcidSlogel (12-tile sight) will open on you from across a room, while you can slip within a few tiles of a Gloth Pup (4-tile sight). Most things sit at 8.
- Night is a double-edged raid. The -3 vision at night lets you approach closer, but your own units are just as blind - bring Night Vision if it is available.
- Let melee hold aggro. Melee generates ~30% more threat than ranged, so a front-line body keeps monsters off your squishier ranged and casters.
- Stealth to reset, not to farm. A Stealth potion breaks contact cleanly, but the first hit you land drops it.