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/.
The third-party open-source licenses, inside the app.
- About Loop Studio → Third-party open-source licenses shows the full license text of every third-party component the build includes, in its original English, in the same dialog; Back returns to About
- Offline too: the installed app has the text precached, and the single-file version carries it inside the file; the web and installed builds also open it as a text file
- Loop Studio's own notice is unchanged: the licenses cover the included components only
A fix release: the Temporary session button looks like the menu buttons beside it.
- The same height, corners, text size and colours as the toolbar's menu buttons, and their hover and keyboard focus; its orange border still marks a temporary session
A fix release: share links use the browser's own compression.
- Share links are compressed with the browser's built-in Compression Streams; the bundled compression code is removed. Existing links still open and the link format is unchanged
- A browser without them makes no link and says so, and the open diagram is kept
- Password-protected share links — an optional password encrypts the diagram inside the link, in the browser; the password is asked for before anything from the diagram is shown, and a lost password cannot be recovered. A plain link is still the default
See CHANGELOG.md for the full notes of these releases, v0.16.0 (the
storage gate, temporary sessions and the Storage and privacy area), the v0.15 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.
Loop Studio includes third-party open-source components. Their licenses are in the app
(About Loop Studio → Third-party open-source licenses) and in every build
(licenses/README.md); they cover those components only.