It is 09:00. You are on call. A stampede of bison is about to hit the Banana Cache, a worm is reaching across the vines, and the certificate on the Auth Gate expires in fifty seconds. The Watchtower can see some of it coming. Not all of it.

• 🎮 How to play
• 🧠 What it teaches
• ⚙️ How the game code works
• 🛠️ Build and run it yourself
• ✏️ Change the game without recompiling
• 📖 Documentation
• 🙏 Credits and licences

You run a small crew through an 8-minute shift (09:00 → 17:00 on the game clock). Things break. You read the symptoms, send someone, pick the response, and race the ⏳ Time to Loss.

Pick a response and a crew member runs it straight away, in about 2.5 s. They still travel to the node on the map, but nothing waits for them. Each runs one thing at a time, so the whole crew can work five problems at once.

Every problem starts somewhere for a reason ("A botnet of a million bison found the Banana Cache on the open internet") and, left alone, spreads along its links as its timer runs down.

• 🟡 Warning: nothing is broken yet. Prevent it (renew the cert, canary the deploy) for bonus points.
• 🔴 Incident: the origin. It's degraded and counting down; at 0 it goes down.
• 📉 Symptom: a neighbour suffering from it. Nothing to fix there: O jumps to the origin, and fixing the origin clears every symptom at once.
• 🐛 Worms are contagious: they infect neighbours for real.
• 🩶 Unreachable: fine, but cut off because the only path runs through a down node.

Pick one of four responses. The terminal types the real command, streams its output, runs a health check, and then says ✅ CORRECT, 🩹 PARTLY (it bought time) or ❌ NOT THE FIX, with the reason. Not sure? 🍌 H spends a banana on a hint, or 🔍 I diagnoses every option.

Network health is the network right now. Shift SLA is its average over the shift, and you need 95% to pass and unlock the next level. At the end you get your score, ✅ what went right, ⚠️ what went wrong (with specifics such as "メインルーター Router went down when its Time to Loss ran out, cutting off 27 other service(s)"), and your shift history.

Enter start · Space most urgent · Tab cycle problems · 1-4 respond · I diagnose · H 🍌 hint · O go to the origin · Z X C V N pick a crew member · G send · arrows hop nodes · Q/E islands · WASD/drag pan · wheel/pinch zoom · F follow

📱 On a phone: drag, pinch, tap a node, tap a response. Off-screen nodes become pins on the screen edge. Tap one to fly there.

▶ Jump straight into a situation: DDoS on the Banana Cache · a deploy that migrated the database · a certificate about to expire · DNS down

Full rules: docs/gameplay.md

Under the jungle paint, every fault is a real production failure and every right answer is the first move an experienced operator would make. All 18 fault types →

It also teaches the shape of on-call: triage, delegating to people with different strengths, not burning out your crew, and reading the symptom before grabbing a tool. "Time to Loss" is the game's own term, and the field guide is explicit that it is not IP TTL or DNS TTL.

 game/data/*.json ──▶ data.rs ──▶ sim.rs (the rules: no Bevy, fully testable)
   tuning · islands ·              ▲   │ health, faults, crew, director, log
   nodes · world · npcs            │   ▼
                    keys/clicks ─ ops.rs (HUD, Time to Loss, overlays, pins, input → orders)
                                   │
           world.rs · water.rs · clouds.rs · npc.rs · view.rs · ui.rs   (Bevy ECS: drawing)

• Bevy 0.20, Rust → WebAssembly → WebGL2. One isometric projection function, one terrain mesh per diagonal row so depth sorting is exact, a texture atlas for the tiles. → docs/engine.md, docs/world.md
• sim.rs is the whole game model, with no engine. Each frame the screen calls Sim::step(dt) and draws the result. A separate native crate, game/simtest/, compiles the same file and runs 14 rule tests plus a balancing harness with bot players (Idle / Novice / Beginner / Expert × 4 levels × 20 seeds). → docs/simulation.md
• Health is a graph walk. After every change a breadth-first search from the core router marks what's reachable. Anything cut off is Unreachable, so root causes and impacts never get mixed up.
• An incident director deals new trouble only after a grace period, under a per-level budget, and never while the network is already on its knees.
• Workers route over the links with Dijkstra (flyers go straight). The game picks whoever would finish first unless you choose.
• One event log groups related events ("27 services unreachable" is one line, not 27).
• The map is data. tools/gen-world.py turns islands.json + nodes.json into the archipelago: one river from void to void, canyons where islands rise above it, vine bridges, free-floating islands, hanging pixel vines.

rustup target add wasm32-unknown-unknown
cargo install wasm-bindgen-cli --version 0.2.129 --locked   # must match game/Cargo.lock
tools/build-web.sh                     # builds into web/game
python3 -m http.server -d web 8080     # open http://localhost:8080

Run the rules tests and the balancing table (native, no browser needed):

cd game/simtest
cargo test --release
cargo run --release --bin balance

A release build needs a few GB of disk and takes a while the first time (Bevy is big). The live site also runs inside a small Next.js host page (app/page.tsx). tools/deploy.sh is the author's own deploy to their server.

Everything worth tuning is JSON in game/data/, fetched when the page loads:

Edit, run python3 tools/gen-world.py (if you touched the map), copy into web/game/data/, and reload. A broken file falls back to the built-in copy, so a typo can't take the game down. Add a fault in JSON and it's in the game, in the docs (tools/gen-docs.py), and in the deep links.

• Engine: Bevy (MIT/Apache-2.0) and the Rust crates listed in docs/assets.md.
• Emoji: Twemoji graphics © Twitter / X Corp. and contributors, CC-BY 4.0, in the Twemoji Mozilla colour font build.
• Fonts: DejaVu Sans Mono (Bitstream Vera licence) and Noto Sans Mono CJK JP subset (SIL OFL 1.1).
• Tile sprites and grid background: from the project's original v0.dev prototype. Their provenance wasn't recorded; see docs/assets.md.

Made by LuckyMonkey 🐒🍌