An incremental systems design game for software engineers.
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Source
You found a startup with one virtual machine in a garage. Users send requests. You wire Components on a board, choose the language and runtime each server runs, and fix one bottleneck after another, until the company serves billions of people and goes public.
Every mechanic is based on real system behavior. PHP-FPM workers wait on the database. A Node.js event loop stalls on bcrypt. A JVM is slow until it warms up. A cache stampedes when it restarts. An average hides the p99. If you have been paged at 3 AM, you know the problems. The game asks you to fix them with numbers.
Quorum has no accounts. A Company lives in your browser, and you can copy it as text from Settings to move it or keep a backup. It runs in Chrome, Firefox, and Safari, and the Board needs WebGL. A larger screen gives the Board more room.
The Quorum Wiki is the manual and a free systems design reference. It explains every Component, every Incident, and the real behavior behind each rule. Start with Play your first Company, read the design document, or check the reality check before you trust a number.
The first Company is one Users node, one App Server, Payments, and Analytics. Requests flow along the Links you draw. Served requests earn Cash, which waits in the Payments drawer until you collect it. Analytics samples traffic and turns it into Insight, the research currency.
The Simulation is a flow network. At any time, one Node limits the most revenue, and the Board marks it. Its card says why: out of CPU, credits, RAM, workers, or connections. Each kind of limit needs a different fix, and more hardware fixes only some of them.
Each fix moves the bottleneck. Faster App Servers send more queries to the Database. A Cache removes Database load and adds stale reads. A Read Replica adds read capacity and adds replication lag. The bottleneck is the content.
No option strictly beats another. Each App Server runs a Stack: a runtime and a framework. Go handles many idle connections cheaply, and its garbage collector takes CPU when the heap fills. Rust is fast and slow to write. PHP-FPM is slow per request and cannot leak memory between requests. The right choice depends on your Design.
Insight buys Research: new Components, runtime variants, techniques, and more visibility. Users grow while Apdex stays above the Era target, and they leave when it drops.
At each Milestone, investors offer a Funding round: Cash for Equity. Each Era brings new request kinds that break the Design in a new way.
| Era | Leave at | New request kinds | New failure mode |
|---|---|---|---|
| Garage | 1,000 users | page, read |
One box runs out of CPU, then RAM |
| Pre-seed | 5,000 users | write, login |
Database contention, connections, CPU-heavy work |
| Seed | 25,000 users | search, upload, bot |
Unlike workloads, abuse, large payloads |
| Series A | 150,000 users | media, rt, buy |
Zone failures, egress cost, money correctness |
| Series B | 1,000,000 users | job, report, ai |
OLTP against OLAP, GPU economics, team scaling |
| Series C | 10,000,000 users | feed, hook, push |
Fan-out, hot keys, geography, region failures |
| Pre-IPO | 50,000,000 users + IPO | — | Compliance, disaster recovery, margin |
| Public | Endless | — | Quarterly guidance |
An incident director tests the weakest part of your Design: a zone outage, a cache stampede, a retry storm, a CVE. Each Incident ends in a Postmortem with one action item. Handle an Incident type by hand, and you can write a Runbook for it.
Advice, offers, invoices, CVE disclosures, and spam arrive in the Inbox as letters from people and systems in the game. Some carry action buttons. Some are traps.
A Company ends in an Exit: an acqui-hire, an acquisition, an IPO, or stepping down. Equity times Valuation pays Legacy. Legacy buys permanent Perks, and your saved Playbooks carry into the next Company. Exits unlock new Ventures, such as Fintech, Streaming media, or an AI startup, and Mutators that make a Company harder for more Legacy.
- Sandbox. Guided Sandboxes teach one mechanic each from a fixed Design, such as Connection Limit, Stampede, GC Pauses, or Hot Key. The free Sandbox has everything unlocked.
- Challenges. Fixed puzzles scored on cost, tail latency, and complexity. Your best result stays in this browser. Server verification and percentiles wait for accounts.
- Wiki home — the manual, the guides, and the reference.
- Game design document — the full design, from simulation to balancing.
- Reality check — the real behavior behind each rule.
- Engineering glossary — the engineering terms the game teaches.
To report a bug, propose an idea, or build the game from source, read CONTRIBUTING.md.
Quorum is free and has no ads. One developer builds most of it, with help from contributors. If it taught you something or cost you an evening, you can buy me a coffee on Ko-fi. Supporters are thanked on the wiki.
Quorum is licensed under the GNU General Public License v3.0 or later.