Loop Studio is a browser-based visual systems editor and simulator — draw a Machinations-style diagram of pools, sources, drains, gates, and converters, then run a deterministic, seeded simulation to see how the system behaves over time. Built primarily for game economies, the same step-based model generalises to inventory/supply chains, service queues, cash flows, and other resource-flow systems; it's an independent, client-only implementation — nothing is uploaded, the whole app runs in your browser, and a graph is a plain JSON file you own. Work is kept in your browser profile only when you say it is your own browser; on a shared computer a temporary session neither reads nor saves stored work, author information or settings (docs/storage-sessions.md).
Run it now: https://cozy-loop-studio.pages.dev — available in 18 languages, with five bundled Templates ranging from a small production flow to a large game economy and a three-zone probability/pity comparison.
- Visual diagram editor — pools, sources, drains, gates, and converters; resources move between them on a deterministic, discrete-step simulation; select a region of nodes from the rail and move them together, or place nodes in a named frame that moves with its contents
- Seeded RNG + Monte Carlo — probabilistic gates and flows, and many-run outcome distributions with percentile bands
- A small model language —
parameter/registernodes with a safe arithmetic expression grammar, guided@-autocomplete authoring, and a name-and-value read-back - Executable state connections —
trigger(+ delay),activator, andlabelPool modifiers, with in-canvas pulse / tint / flash feedback - Simulation playback — resources visibly depart, travel the real edge path, and arrive before values update, in dependency order
- Data import & collaboration — bring the numbers you already keep in a
spreadsheet (CSV/TSV paste or upload) in as adjustable Parameters, with a
manual refresh and a three-way diff — see
docs/import-guide.md; plus file-based project revisions & proposals for asynchronous collaboration — no accounts, no server - Runs anywhere — an installable offline PWA, a portable single-file build, shareable links (optionally protected with a password), and a UI translated into 18 languages
The UI ships in 18 languages, listed here the way the in-app picker orders them. Pick one under Settings → Language; the first visit follows your browser's language, and the choice is remembered on that device.
| Code | Language | In its own words |
|---|---|---|
ar |
Arabic | العربية |
zh-Hans |
Chinese (Simplified) | 简体中文 |
zh-Hant |
Chinese (Traditional) | 繁體中文 |
nl |
Dutch | Nederlands |
en |
English | English |
fr |
French | Français |
de |
German | Deutsch |
it |
Italian | Italiano |
ja |
Japanese | 日本語 |
ko |
Korean | 한국어 |
pt-BR |
Portuguese (Brazil) | Português (Brasil) |
pt-PT |
Portuguese (Portugal) | Português (Portugal) |
ru |
Russian | Русский |
es-419 |
Spanish (Latin America) | Español (Latinoamérica) |
es-ES |
Spanish (Spain) | Español (España) |
th |
Thai | ไทย |
tr |
Turkish | Türkçe |
vi |
Vietnamese | Tiếng Việt |
Regional pairs are separate locales, not one catalog with a flag: a browser
asking for pt-PT gets European Portuguese, while pt, pt-BR and the
African Portuguese tags get Brazilian — and the same split holds for the two
Spanish and the two Chinese catalogs. See
docs/localization.md for the resolution order and
the per-locale notes.
The 3-zone gacha banner comparison Template runs three pity/pickup rule sets — General/Free, Premium Standard (hard-pity ceiling), and Premium Pickup (hard-pity + a pickup guarantee) — side by side, 200 pulls per zone under identical run settings. Once a run completes, its hit and pickup rates are easy to compare; run Monte Carlo analysis to inspect the distribution across many runs.
Premium Pickup, framed on its own — the hard-pity counter forces the next
roll's SSR once it hits the ceiling; whether that (or any ordinary) SSR lands
as pickup or standard depends on the Pickup owed guarantee flag, which a
miss sets and the next SSR consumes.
npm install
npm run dev # http://localhost:5173
npm run build # -> dist/ static SPA, deploy anywhere
npm run build:portable # -> dist-portable/ single self-contained index.html (file://)
npm run lint
npm test # vitest (engine + store unit tests)
npm run e2e # Playwright browser end-to-endRequires Node 22+ (.nvmrc pins 22). React + TypeScript + Vite,
React Flow for the canvas, Zustand for state; the
simulation engine is a dependency-free, unit-tested TypeScript module kept
separate from the UI. Deployed on Cloudflare Pages; CI on GitHub Actions.
Behaviour is frozen in versioned spec documents; a behavioural change means a new spec id, never an edit to a frozen one.
- Engine & simulation —
SEMANTICS.md,SEMANTICS-B1.md(seeded RNG),SEMANTICS-B2.md(Monte Carlo) - State connections —
SEMANTICS-S4.md(trigger/activator/label; the latest of a sequential S1→S4 series, each frozen on its own) - Model language & expressions —
SEMANTICS-X.md,SEMANTICS-M2.md(the latest of a sequential M1→M2 series) - File formats & revisions —
SEMANTICS-W.md(Workspace),SEMANTICS-U.md(Share links, with errata),SEMANTICS-P.md(password-protected share links),SEMANTICS-R8.md(revision projection/diff/Apply — the latest of a sequential R1→R8 series)
Project revisions & proposals — a worked, file-based walkthrough of the
create → propose → review → apply flow lives in
examples/revision/README.md.
Where the model could grow (not on a committed schedule — continuous-time
models, spatial/grid models, external-engine integration for specialized
physics) is recorded in docs/product-direction.md.
Additional feature-specific design documents (localization, mobile, module
system, large-graph readability, simulation playback, edge routing, data
import, …) live under docs/.
A fix release: the buttons' symbols are the app's own icons.
- Every functional icon is drawn by the app, not by an operating-system font, so Play, the lock, the menu arrows and the rest look the same on Windows, iPhone and everywhere else
- Names are words: no symbol is read out before a label, and the Reset and Step buttons have names
A fix release: the theme you chose comes back when the app starts.
- The saved theme is applied at start-up, without opening Settings; an unreadable value follows the system theme
- No light flash before a dark start: the theme is read in the page head, before anything is painted
A fix release: the playback bar keeps to its space at narrow widths.
- On a phone, the run bar no longer covers the bottom of the canvas when its buttons wrap to a second row; the Timeline sheet, the More sheet and the zoom buttons stay above it whatever its height
- In a narrow desktop window, the playback controls are no longer cut off at the bottom of the window
- An update notice — after an update, a browser that has used Loop Studio before sees one line naming the new version; it takes no focus, changes nothing and never times out
- What's new, in the Help menu — every release note, newest first, in all eighteen
languages, offline; a
Newmarker stays until the newest entry has been opened - A clearer Help menu — grouped by purpose, with items named for what they do:
Restart the tour,Turn contextual tips back on - A Timeline series selector — choose which series the chart draws; a document with no saved choice draws the first eight instead of every line
- A refreshed light theme — one calm palette, rounder panels and a clearer keyboard focus indicator; the dark theme is unchanged
No migration: a v0.14.0 file opens unchanged. From this release on, a visible change ships
with its version and its release note in the same change — see
docs/release-notes.md.
See CHANGELOG.md for the full v0.15.2, v0.15.1 and v0.15.0 notes, the
v0.14.0 and v0.13.0 releases and every earlier one.
Created by Hanrim · Cozy Shelter.
Loop Studio is an independent project and is not affiliated with or endorsed by Machinations.io. Its modeling approach is informed by publicly documented academic work on game-economy diagrams.
Copyright © 2026 Hanrim. All rights reserved.