3D Horror - Core (Make game skill)

Part of the make-game skill. The skill links here when your agent needs the detail.

First-person horror blueprint: game state, the vulnerable-player controller, flashlight mechanics, level building, lighting, and the minimal HUD. The stalker AI, tension/atmosphere system, procedural audio, and interactables live in 3d-horror-systems.md. The player scene reuses the 3d-fps hierarchy and controller (yaw on root, pitch on Head, two crouch shapes, headbob) - see 3d-fps.md. This file covers what horror changes.

Design law: vulnerability

No weapon, ever. The flashlight is the only tool. The moment the player can fight back it becomes an action game. No health bar, no minimap, no kill counter - the HUD shows only battery, interaction prompt, and notes.

Minimum playable base (build this first)

One dark room + flashlight pickup + a locked door + the key that opens it. Prove “dark, need the light, find key, open door” before any AI or atmosphere exists.

Autoloads

Two: GameManager and AudioManager, both process_mode = PROCESS_MODE_ALWAYS. GameManager is the single source of truth:

enum GameState { MENU, PLAYING, PAUSED, GAME_OVER, ESCAPED }

var inventory: Array[String] = []
var notes_found: Array[String] = []
var has_flashlight: bool = false
var flashlight_battery: float = 100.0
var doors_unlocked: Array[String] = []
var tension_level: float = 0.0        # 0 calm .. 1 max
var is_reading_note: bool = false

set_state() pauses the tree for PAUSED/GAME_OVER/ESCAPED, unpauses on PLAYING, and force-closes any open note on leaving PLAYING.
Tension rises passively 0.005/sec while PLAYING; systems spike it via increase_tension(amount). Everything atmospheric reads this one float.
Note reading is a modal state: while is_reading_note, the player controller AND the stalker both stand down (safe reading).
Inventory is just string ids: add_item / has_item / remove_item; open_note(id, text) / close_note() emit signals the HUD listens to.

AudioManager: 8 pooled AudioStreamPlayers on an “SFX” bus, dedicated ambient + music players on an “Ambient” bus, buses created at runtime via AudioServer.add_bus() if missing. play_ambient crossfades from -40dB. Bus separation is mandatory - you cannot balance or add reverb/low-pass later without it.

Player controller (horror deltas from 3d-fps)

Walk 3.0 / sprint 5.0 / crouch 1.5 (slow = vulnerable; FPS-speed movement kills dread).
gravity_multiplier 1.5 - heavier, grounded.
ALL input gated on GameManager.current_state == PLAYING in both _unhandled_input and _physics_process - frozen during notes, pause, game over.
Extra child under Camera3D: Flashlight (SpotLight3D at (0.15, -0.1, -0.1), hidden until picked up) + FlashlightDust (GPUParticles3D).
Input map adds flashlight (F); no shoot/aim/reload.
Footsteps route through the procedural audio footstep with random pitch.

Flashlight (the core mechanic)

func _handle_flashlight_drain(delta: float) -> void:
	if not flashlight_on:
		return
	GameManager.flashlight_battery -= flashlight_drain_rate * delta / 60.0  # 15%/min, ~6.5 min life
	GameManager.flashlight_battery = maxf(GameManager.flashlight_battery, 0.0)
	if GameManager.flashlight_battery < 15.0:
		# dual-sine = irregular organic flicker, not a metronome
		var flicker := sin(Time.get_ticks_msec() * 0.03) * sin(Time.get_ticks_msec() * 0.07)
		flashlight.light_energy = lerpf(0.3, 1.2, (flicker + 1.0) * 0.5)
	else:
		flashlight.light_energy = 1.5
	if GameManager.flashlight_battery <= 0.0:
		flashlight_on = false
		flashlight.visible = false

Toggle refuses until GameManager.has_flashlight. Battery pickups restore +30. Drain rate is the game’s difficulty dial. Dust in the beam: GPUParticles3D (60 particles, 4s life, box emission 2x1.5x5 in front of camera, tiny unshaded spheres radius 0.008, alpha ramp peaking at 0.08). Emits only while the flashlight is visible. Reads as volumetrics at a fraction of the cost.

Breathing (fear you can feel)

func _handle_breathing(delta: float) -> void:
	var target := 0.0
	if stamina < 30.0:
		target += (1.0 - stamina / 30.0) * 0.5
	target += GameManager.tension_level * 0.3
	breathing_intensity = lerpf(breathing_intensity, target, 2.0 * delta)
	if breathing_intensity > 0.05:
		var t := Time.get_ticks_msec() * 0.001
		camera.rotation.x += sin(t * 1.5) * breathing_intensity * 0.003
		camera.rotation.z = lerpf(camera.rotation.z,
			sin(t * 2.0) * breathing_intensity * 0.002, 3.0 * delta)

Involuntary camera sway from low stamina + high tension. Subtle numbers - resist cranking them.

Level building (library first, primitives last)

The level comes from real assets: route it through the asset-strategy skill (assets.search, then summer_import_asset / summer_import_asset_by_id) and look for a ready horror location (an abandoned house, a haunted forest, a modular horror-house kit) plus period props, keeping one coherent style. Import the location that fits and build gameplay inside it. Do NOT grey-box a level a real asset already provides. Runtime primitive geometry (BoxMesh/PlaneMesh + StaticBody3D, collision layer 2) is only for what the imported assets lack: interior partitions the imported location does not have, trigger volumes, blockers. When you do need it: WALL_HEIGHT 3.5, WALL_THICKNESS 0.15, helpers _floor(center, size), _ceiling, _wall_x(z, x0, x1) / _wall_z(x, z0, z1), _prop_box(pos, size, mat). Materials: dark desaturated albedo (floor 0.12/0.11/0.1, walls 0.18/0.17/0.15), roughness 0.85. Layout formula:

Entry area - well-lit, flashlight pickup here.
Main hall - central hub, multiple exits, player keeps returning.
Side corridors - long, narrow, dim; stalker territory.
Dead-end rooms - keys and notes; forced backtracking.
Back corridor - darkest, highest tension.
Final area - escape zone at the far end, exit key behind at least one locked door.

Atmosphere rendering settings

WorldEnvironment is half the horror:

Sky near-black (top 0.02/0.02/0.05); ambient color 0.03/0.03/0.05 at energy 0.5 - the player MUST need the flashlight.
Tonemap ACES, white 6.0. SSAO on (radius 2, intensity 3 - darkens corners). SSIL on (radius 3, intensity 0.5). Glow subtle (0.3 / bloom 0.1).
Fog density 0.02 dark; volumetric fog density 0.06, anisotropy 0.7 - this is what makes the flashlight beam a visible cone.

Lighting rules: OmniLights energy 0.4-0.8 (main hall 1.2 max), ALL with shadow_enabled = true (the stalker casts a shadow before you see it). Give each area a distinct temperature - entry warm (0.6, 0.5, 0.3), corridors cool (0.3, 0.4, 0.35), lab sickly green (0.3, 0.6, 0.4) - it is navigation AND variety without textures. Collision layers: 1 Player, 2 Environment, 3 Interactable, 4 Enemy.

HUD (minimal by design)

HUD (CanvasLayer)
  Crosshair (centered dot)
  InteractionPrompt (Label, bottom center, "[E] Open")
  BatteryContainer (top left, HIDDEN until flashlight found)
    BatteryBar (ProgressBar; red <20%, yellow <50%, blue else)
  NoteBackdrop (fullscreen black, 72% alpha)
  NotePanel (centered note text)
  Vignette (fullscreen; alpha = 0.2 + tension * 0.4)

Wire to GameManager signals (note_opened/closed, game_state_changed). Note UX detail: 0.35s cooldown after opening before close input is accepted - otherwise the same interact press that opened the note closes it. HUD hides entirely when state is not PLAYING.

Build order

Autoloads + input map + layers.
Player from 3d-fps base, horror speeds, state gating.
One room + WorldEnvironment settings + flashlight pickup + drain.
Doors/keys/notes + escape zone (3d-horror-systems.md).
Atmosphere controller, then the stalker LAST - it only lands once the world already feels wrong.

Traps

Giving the player any weapon, health bar, or combat UI.
Ambient energy above 0.5 - no darkness, no battery economy, no fear.
Constant jump scares. The template leans on anticipation; one of its five tension events is deliberately NOTHING.
Stalker always visible - players habituate; long gaps are intentional.
Constant music. Silence scares; use the drone + rare stingers, save music for peaks and safe rooms.
Identical rooms - distinct color temperature per area or players get lost and bored simultaneously.
Skipping audio buses - SFX through SFX bus, ambience through Ambient, or mixing and wall-muffling effects become impossible later.

Source: library/skills/make-game/references/3d-horror.md, rendered from summer-engine@4.3.0 on npm.

Overview

2D art

3D models

Agent workflow

AI and NPCs

Animation

Asset pipeline

Audio

Character controllers

Publishing and growth

Debugging

Deployment

Editor

Gameplay

Level design

Multiplayer

Navigation

Performance

Rendering and lighting

Runtime

Scenes and project

Scripting

Tools

UI

Visual effects

Video

3D Horror - Core (Make game skill)

Design law: vulnerability

Minimum playable base (build this first)

Autoloads

Player controller (horror deltas from 3d-fps)

Flashlight (the core mechanic)

Breathing (fear you can feel)

Level building (library first, primitives last)

Atmosphere rendering settings

HUD (minimal by design)

Build order

Traps

​Design law: vulnerability

​Minimum playable base (build this first)

​Autoloads

​Player controller (horror deltas from 3d-fps)

​Flashlight (the core mechanic)

​Breathing (fear you can feel)

​Level building (library first, primitives last)

​Atmosphere rendering settings

​HUD (minimal by design)

​Build order

​Traps

Design law: vulnerability

Minimum playable base (build this first)

Autoloads

Player controller (horror deltas from 3d-fps)

Flashlight (the core mechanic)

Breathing (fear you can feel)

Level building (library first, primitives last)

Atmosphere rendering settings

HUD (minimal by design)

Build order

Traps