An iPhone 11 becomes a haunted field instrument—when the device cannot actually see the room.
Hauntline / iPhone 11 / active investigation
01 · THE DESIGN QUESTION
How do you make a phone feel haunted?
Hauntline started with a constraint: the old iPhone had a camera and microphone, but no LiDAR, no dependable depth and no finished game around it. The answer was to make the device itself part of the fiction. Every limitation became something the player had to read, manage or fear.
THE CORE IDEA
“The phone is not a HUD. It is the haunted object.”
01
Author the room
Walk the real space, draw its corners, and mark the thresholds that connect it.
02
Read the signal
Use EMF, Spirit Box, Thermometer and UV to build a picture that is always incomplete.
03
Lose certainty
SYNCH drains, apparitions interrupt, and the phone starts to feel less like a tool.
04
Stay connected
Manage SYNCH as apparitions and unstable evidence make the phone less reliable.
02 · THE HARD PART
The lack of AR hardware became the first mechanic.
Designing spatial systems on an older iPhone meant replacing invisible machine certainty with visible player-authored certainty. The player does not enter a perfect digital twin; they negotiate with a fragile model of their own room.
01
No LiDAR
There is no instant room mesh. The player draws room corners, floor thresholds and a front-door anchor by hand.
The scan becomes an action, not a loading screen.02
No real depth
Without LiDAR or RoomPlan, the prototype combines player-authored room flags, ARKit and motion tracking to estimate location.
Realign and No Signal make uncertainty visible.03
Old iPhone
Limited performance means controlled apparition timing, restrained compositing and carefully timed feedback instead of spectacle.
Timing becomes the special effect.
One floor. Manual scan. Camera-led, sensor-assisted spatial model. Realign, No Signal, drift, mirrored rooms and room-switch failures were not side notes—they shaped the interaction language.
THE SCAN IS PLAY
The room only exists because the player made it exist.
During setup, the lights stay on and the doors stay open. The player scans each room, draws its boundary and traces its thresholds; once the house is mapped, the investigation can continue in darkness.
The flashlight gives the player just enough visibility to author a room.
03 · THE MECHANIC STACK
The phone is the game.
Hauntline layers a small set of physical inputs into a rising cognitive load. The player is always asking: what did I actually detect, what did the system invent, and how much longer can I stay connected?
01player-authored map
Manual room scan
During setup, keep the lights on and doors open. Scan each room, draw its boundary, trace the thresholds and mark the front-door anchor. Once the house is mapped, continue the investigation in darkness.
02spatial uncertainty
Map recovery
The spatial model can drift, mirror or lose a room. Realign asks for the anchor again; No Signal turns a technical limitation into pressure.
03camera · mic · torch
Sensor choice
EMF, Spirit Box, Thermometer and UV are available throughout the investigation. Switch between them freely; the flashlight and map remain useful, but interference can make the flashlight unreliable.
04certainty as health
SYNCH tension
Start at 100%. EMF spikes, temperature events, UV scans, Spirit Box responses and sustained apparition focus can drain SYNCH. Regular apparitions unlock at 85% or below, approaching apparitions at 60% or below, the critical state at 10% or below, and forced desynchronization at 0%.
05visibility is scarce
UV apparitions
Focusing the camera on an apparition drains 1% of SYNCH every 0.3 seconds. UV apparitions are floor-aligned, may begin just outside the frame, and hold for roughly 2–4 seconds once centered before blinking out.
06observation becomes proof
Evidence memory
The notebook keeps the top three temperature highs/lows, top three EMF readings, Spirit Box replies, UV traces and events per room.
07appearance ≠ identity
Entity logic
Carpenter is the current visible apparition. The proposed roster—Residual, Wraith, Revenant, Chorus, Threshold, Mimic—would shape a future behavior and evidence system.
08implemented · in development
Hunt and banishment
The prototype asks the player to survive the hunt and match the haunted room, rite and hidden type. The evidence balance and entity behaviours are still being tuned.
The beam makes the room readable; the tool dock decides what to trust next.
AVAILABLE TOOLSEMF · Spirit Box · Thermometer · UVSwitch tools freely; the flashlight helps recover room cues, while interference can make it unreliable.
04 · APPEARANCE VS. BEHAVIOUR
What the ghost looks like is not what it is.
The current prototype separates the visible apparition from the hidden type assigned to the case. Carpenter is the appearance; the behaviour-based clues that distinguish entity types are still being tuned.
VISIBLE APPEARANCE
Carpenter
The image the player sees in the camera: a recognizable presence while the underlying identity system is still being developed.
PROPOSED ROSTER · FUTURE SYSTEM
ResidualMemory stain; repeated events and weak UV
WraithStrong EMF; shadows and signal collapse
RevenantFootprints, handprints and close contact
ChorusMultiple voices on the Spirit Box
ThresholdBoundaries distort; voices come through walls
The player survives by changing the relationship with the room.
Rites are not a spell menu. They are the voice-activated layer for temporary edits to attention, noise and access. They give the player just enough agency to keep investigating while the survival loop and balance continue to evolve.
Vox mea ancora est.
Stabilize
Passive stabilizer with a subtle pulse and a 15s cooldown.
+25% SYNCH
Ad lucem redeo.
Return to light
A light veil keeps the flashlight stable and protects against hunts; 80s cooldown.
60s protection
Silentium circum me.
Make silence
Reduces the noise footprint for 30s; 90s cooldown.
70–85% quieter
Limen obsigno.
Seal the threshold
A room only becomes safe when every connecting threshold is sealed; UV sigils turn green.
Safe room
!
ACTIVE HUNT · IN DEVELOPMENT
At 65% SYNCH or lower, the house can turn. Hide in the dark, stay quiet, duck and keep the flashlight off. A sealed room is only safe once every connecting threshold is sealed.
LIGHT + SILENCE = COUNTERPLAY
06 · EVIDENCE → CASE FILE
A haunting becomes a case file.
Every signal is temporary, but the notebook is persistent. It turns an anxious walk through the apartment into a trail of decisions the player can revisit before continuing, saving or ending the case.
UV changes what the camera can hold: the beam anchors the room while the violet filter reveals a trace.
03temperature highs / lows per room
03strongest EMF readings per room
07sSpirit Box reply stack
04UV findings retained per room
THE MEMORY LAYER
The map remembers what the player barely understood.
The map, room memory and SYNCH persist through close and reopen. Continue re-anchors the front door; END CASE or forced desync clears the active run. The current case record stores room geometry, evidence snapshots and room-memory data. Entity identification, rites and banishment are present as prototype systems; their evidence balance and behaviour logic remain in development.
CURRENT BUILDRoom + evidenceContinue → investigation
DESIGN DIRECTIONRoom + rite + typeCorrect match → banishment
Footprints and handprints were prototyped around haunted and adjacent rooms; without reliable depth, their timing and placement remain under evaluation.
07 · PROCESS / PROTOTYPE STATUS
An unfinished build, designed all the way down.
Hauntline is still in development. That is exactly why the process matters: the prototype is a record of how a game can be designed around missing technology, uncertain evidence and the emotional timing of a phone screen.
01
Start with the fear
The question was not how to add ghosts to AR. It was how to make the phone itself feel unreliable.
02
Prototype the verbs
Scan, trace, listen, measure, focus and speak were tested as small interactions before becoming a larger system.
03
Stress the fiction
Drift, mirrored rooms, lost signal, passive room memory and forced desync became design material instead of bugs to conceal.
04
Leave it unfinished
The prototype is still in development. Its value is the behavior model and the decisions it makes possible—not a claim of completion.
The Scanned Zones map preserves the player-authored rooms and provides a front-door anchor for realignment.
CURRENT BUILD
Camera-led, sensor-assisted investigation · one-floor manual scan · Carpenter appearance · voice rites and hunt logic implemented · entity behaviour and evidence balance in development.
THE TAKEAWAY
Designing the ghost was only half the job. Designing the uncertainty was the real game.
