One Sim

A single-POV narrative life-simulation: one person lives a felt life among ~50 others in a cozy 2D town — and every behaviour underneath is driven by a real, equation-backed model from the cognitive-science and simulation literature.

"cozy 2d simulation, but under the hood is the top-tier ideas and theories of what science got so far from real serious papers, not a video game." — the owner's thesis, verbatim.

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What you see vs. what's underneath

What you see is cozy: a hand-composed pixel-art town — a square with a fountain, shops with awnings, a glass office, a clinic, a park with a pond, a cottage row with gardens, ringed by forest. Villagers walk real paths, speak in dialogue bubbles, and sleep under a starfield while the sky runs dawn→dusk, weather falls, trees turn with the seasons, and windows glow at night. You watch one being live it from the inside — or flip to observer mode and click anyone in the town.

What's underneath is not a bag of if statements. Every mood, every drifting friendship, every bad night's sleep, every rumour and false belief is produced by a named model — a real paper or theory, reduced to a deterministic, bounded equation and pinned by a test that fails CI if the claim stops being true. The cozy surface is the point; so is the refusal to fake the machinery beneath it.

The science — the part that matters

Each mechanism below is a faithful reduction of its source — the right equation or the right structural claim, not a full-fidelity biology. Every one reaches the being's perception each tick, and every one ships a deterministic scripted twin so reproducibility never bends. The full science → code → enforcement audit trail is in sim/REALISM_REPORT.md §10; the simplifications we knowingly made are written down there rather than hidden.

Emotion — a differentiated inner weather

Mechanism	The paper / theory	How it shows up in the life
PAD three-axis mood · emotion.py	Mehrabian & Russell — pleasure/arousal/dominance affect space	Mood stops being one number; anger (−P +A +D), fear (−P +A −D) and grief (−P −A −D) become distinct feelings
OCC-lite appraisal · emotion.py	Ortony, Clore & Collins — appraisal theory	Each event is named: the same slight lands as resentment for one person, shame for another
Emotion → action tendency · agent/disposition.py	Approach/avoidance motivation (OCC · Roseman · Elliot)	The same blow is met head-on by a high-dominance temperament and fled by an anxious one
Big Five / OCEAN · personality.py	Costa & McCrae — five-factor model	One personality vector steers mood set-point, dialogue, habit and schedule; two lives diverge from the same seed

Memory — a life, not a log

Mechanism	The paper / theory	How it shows up in the life
ACT-R activation & decay · state/stores.py	Anderson — ACT-R memory activation (frequency + recency)	The sim genuinely forgets: a twice-remembered moment outlives a one-off; core memories never fade
Conway chapters · brain.py (nightly consolidation)	Conway — the Self-Memory System	A sleep pass rolls episodes into general events and lifetime chapters — a life becomes narratable, not searchable
Reconsolidation · two-record stores	Memory reconsolidation — retrieval re-stores, coloured by the present	The remembered past drifts under mood while the factual record never does ("what happened / what she remembers")
Typed memory · agent/brain.py	MemGuard — typed memory (arXiv:2605.28009)	One bad night isn't filed as "he's always angry": traits, relationship-facts and raw episodes are kept apart

The body & the year

Mechanism	The paper / theory	How it shows up in the life
Two-process sleep · sleep.py	Borbély (1982) — homeostatic pressure S + circadian process C	Waking is threshold-driven by sleep pressure and chronotype; a short or broken night is felt as grogginess
Photoperiod / seasonal affect · world/globals_state.py	Seasonal affective disorder; Rosenthal et al. (1984)	The dark of the year sits an anxious soul lower — day-length held apart from weather
Allostatic load · allostasis.py	McEwen & Stellar — allostatic load (chronic-stress wear)	Sustained stress accumulates as standing wear that heals slowly and later raises illness risk

The social body — a town, not a star

Mechanism	The paper / theory	How it shows up in the life
Dunbar layers · npcs.py	Dunbar — the number and its relationship layers	Everyone keeps ~5 close + ~15 warm ties; beyond that bonds decay — nobody has 49 friends
Weak-tie gossip · npcs.py	Granovetter (1973) — The Strength of Weak Ties	News reaches you through bridging acquaintances, not the clique; rumour favours the weak ties
Friedkin–Johnsen opinions · opinion.py	Friedkin & Johnsen; bounded-confidence clustering (Hegselmann–Krause 2002)	Opinions, not just facts, move: cliques come to agree; the street can be "of one mind" or "split"
Network SIR contagion · lifecycle.py	Kermack–McKendrick SIR on a graph (Pastor-Satorras & Vespignani)	Illness spreads person-to-person along the Dunbar contact graph — an outbreak can thin the whole town

Mind, world & story

Mechanism	The paper / theory	How it shows up in the life
Spatial perception · perception.py	Line-of-sight / earshot within a place (structural — no single source)	Sharing a room isn't sharing the moment: a scene splits into who is seen / overheard / unaware
Theory of mind & false belief · tom.py	The Sally–Anne test (Wimmer & Perner 1983; Baron-Cohen, Leslie & Frith 1985)	You still think Devi's at the café until you see otherwise — a false belief persists, then corrects with a jolt of surprise
Homophily attraction · romance.py	Homophily (McPherson et al. 2001); similarity-attraction (Byrne 1971)	The town falls in love along P ∝ exp(−Δtrait²/τ²) — drawn toward those near its own temperament
Drama-manager pacing · director.py	Façade beat-sequencing (Mateas & Stern 2003); the RimWorld / Left 4 Dead storyteller lineage	After a heavy stretch the next charged beat is held back — a breather — pacing the story across seeds

Under these sit the structural layers built earlier in the program: the POV authors a day-plan and can amend it; the town is a real web of NPC↔NPC bonds (homophily-seeded, Dunbar-capped); the economy closes its loops and reconciles money to the cent daily; the population turns over by birth → illness → death → arrival (children inherit blended temperament; estates pass on), and the single life you follow can itself end — age- or illness-driven, rendered with restraint rather than a game-over; and fractal time applies the salience idea to time itself, montaging low-salience days so a year is watchable in an evening. Sources and the field survey (Stanford Generative Agents → Project Sid → 2026) are in sim/REALISM_REPORT.md; the shipped blueprint is sim/REALISM_UPGRADE_PLAN.md.

The determinism firewall — the engineering spine

Real science, to be worth the name, has to be reproducible — so the whole build stands on one load-bearing invariant:

• The scripted provider is fully deterministic: same seed → byte-identical run. All 577 tests, the golden scenes, the 500-tick audit and the reproducibility check run on it — and a run can be saved and resumed byte-identically, even across processes.
• Every LLM mechanism ships a deterministic scripted twin. A live local model may only ever change the words — never the RNG stream, never an effect, never a state transition.
• Isolated RNG streams keep the POV's reproducible narration separate from the crowd's social draws; live voicing runs after all bookkeeping so it can only swap text.

That is what lets the science be enforced rather than asserted: validate.py is ALL GREEN — golden 15/15 · audit 18/18 · probes (6 categories) · emergence 10/10 across seeds — and an emergent story only counts once it recurs across seeds.

Watch it live

Runs with no model out of the box (the deterministic narrator) or against a real local model via LM Studio — no cloud, no API keys. If LM Studio isn't reachable it falls back to scripted and says so.

Windows, one click: double-click sim/start.bat — it serves the launcher at http://127.0.0.1:8642 and opens your browser; stop.bat shuts it down.

Manual (from the sim/ directory):

python -m venv .venv
.\.venv\Scripts\Activate.ps1        # if blocked: Set-ExecutionPolicy -Scope Process -Bypass, then retry
pip install -r requirements.txt

python launch.py                    # ★ web launcher + 2D animated town at http://127.0.0.1:8642
python run.py --ticks 60            # or terminal mode, ~a day, no model needed
python validate.py                  # golden 15/15 · audit 18/18 · probes · emergence

# macOS / Linux
cd sim && python -m venv .venv && source .venv/bin/activate && pip install -r requirements.txt
python run.py --ticks 60

The deps live in .venv, not global Python. ModuleNotFoundError: No module named 'mesa' means the wrong interpreter — activate the venv or call .venv/Scripts/python.exe directly.

To run live, pick LM Studio for both the mind and the NPC minds in the launcher (LM Studio up on localhost:1234 with the models loaded). Full detail — the watch-it layer, the four dials, the observer mode, the module→design-doc map — is in sim/README.md.

Repository layout

• sim/ — the runtime: Mesa/Python, stdlib-only server, vanilla-JS pixel-town frontend, SQLite state, local-first LLM. This is what you run. See sim/README.md.
• SIM_WORLD_DESIGN_Edition11_FINAL/ — the canonical, engine-agnostic design package (folders 00_START_HERE → 10_runtime_design): the world and the machine that runs it, specified as a source of truth the runtime binds to. Start with the World Design Compendium.
• Key docs — BUILD_STATUS.md (what's built · current truth) · sim/REALISM_REPORT.md (the science mapping) · sim/REALISM_UPGRADE_PLAN.md · sim/LIVING_TOWN_PLAN.md · sim/MODELS.md.

Status & credits

• Phases 2–17 shipped. The watch-it layer + dialogue (6), the ~50-person world met by living (7), the Living Town — OCEAN minds · locations/timetables · closed-loop economy · pixel-art observer (8), the will-and-weave / autobiography / a-year-in-the-town / a-life-whole structure (9–12), and the deep-realism program above (13–17).
• Since then: a realistic gender mix across the town, the POV's own mortality, and byte-identical save / resume of a running life.
• 577 tests, all on the deterministic scripted provider; validate.py ALL GREEN — golden 15/15 · audit 18/18 · probes 6 categories · emergence 10/10. Single source of truth: BUILD_STATUS.md.
• Runs with no cloud. No model needed (deterministic), or a local LLM via LM Studio — no keys, nothing leaves the machine.
• Art: CC0 pixel art by Kenney (RPG Urban Pack + Roguelike Modern City), committed under sim/static/assets/. Requires Python 3.10+ and Mesa; everything else is stdlib.
• License: no project license file is declared in the repo yet.