A simulation game for teaching Green IT – from code to portfolio. It runs in the browser and as a desktop app for Windows, macOS and Linux (Android and iOS later). It has three tracks. In Operations you run a data center: switch off idle servers, move flexible work into clean hours, cool wisely, renew hardware where it pays off. In Engineering you improve the software that runs in it: measure before you optimize, cache what repeats, use AI models only as large as needed. In Portfolio you look at the IT of a whole organisation: take stock of its emissions, choose the measures that pay off first and tidy up the application landscape. Serve your users reliably and emit as little CO₂ as possible.
The game is a simulation, not a race: pause at any time, plan in peace, and let time run faster when nothing needs to be decided. Each scenario introduces one idea and names its technical term; a debrief compares your result with a reference operator and shows "what if" with other rules.
Play it in the browser: https://diavolezza.github.io/LoadShift/ (built from main on every push). No sign-up;
the progress stays in the browser.
| Operations | Engineering | Portfolio |
|---|---|---|
 |
 |
 |
Teaching with it: docs/TEACHING.md. Feedback and ideas are welcome as issues.
The app speaks English and German (switch on the start page); everything in this repository is written in English.
| Operations | Term | |
|---|---|---|
| O1 | Night shift | Rightsizing |
| O2 | Wait for the sun | Time Shifting |
| O3 | When the wind drops | Carbon-Aware Scheduling |
| O4 | Headroom | Autoscaling |
| O5 | Consolidation | Consolidation (Bin Packing) |
| O6 | Heat wave | PUE (Power Usage Effectiveness) |
| O7 | Old iron | Embodied Carbon |
| O8 | Training run | Carbon-Aware Training (Power Capping) |
| O9 | Eco mode | Demand Shaping |
| O10 | Two sites | Location Shifting |
| O11 | Green on paper | 24/7 Carbon-Free Energy |
| O12 | Dark doldrums | Carbon Awareness |
| Engineering | Term | |
|---|---|---|
| E1 | How many nines? | Availability Tactics |
| E2 | Measure first | Profiling |
| E3 | Growing data | Algorithmic complexity |
| E4 | Hit or miss | Caching |
| E5 | Data diet | Sustainable Web Design |
| E6 | Keep everything? | Data Lifecycle Management |
| E7 | Chatty services | Green Software Architecture |
| E8 | Constant asking | Polling, Push, Streaming |
| E9 | One per customer? | Multi-tenancy (Silo, Bridge, Pool) |
| E10 | Right-sized AI | Green AI (Right-sizing Models) |
| E11 | Green pipeline | Green CI/CD |
| E12 | One pattern for everything? | Architecture patterns in context |
| Portfolio | Term | |
|---|---|---|
| P1 | Inventory | Carbon Accounting |
| P2 | Where to start | Marginal Abatement Cost Curve (MACC) |
| P3 | Tidy up with TIME | Application Rationalization (TIME) |
| P4 | Leave the cloud? | Cloud Repatriation |
In German the operations scenarios are called B1–B12 ("Betrieb"). The three tracks are independent of each other. Inside a
track a scenario opens with a star only where it builds on another one: in Operations B1–B4 one after the other, then
the rest after B4 and the capstone B12 after B8; in Engineering E3 after E2; in Portfolio P2 after P1. The progress
can be reset in the About dialog. A player who is stuck can uncover the solution on the
end card and put it into the task. The start page continues with the next open
scenario and shows one tab per track; a glossary collects every technical term. docs/CONCEPT.md, section 9.4, maps every scenario to the learning goals of the
iSAQB Advanced Level module GREEN, for courses that follow it.
- A JDK, version 21 or later, for example Eclipse Temurin. Check with
java -version. Nothing else has to be installed: the Gradle wrapper (gradlew,gradlew.bat) downloads Gradle, Kotlin and all libraries on the first build – this needs an internet connection and takes a few minutes. - For the web version a current browser with WebAssembly GC: Chrome or Edge 119+, Firefox 120+, Safari 18.2+.
macOS and Linux:
./gradlew :composeApp:run
Windows:
gradlew.bat :composeApp:run
To try it out, the development server builds the app and opens it in the browser:
./gradlew :composeApp:wasmJsBrowserDevelopmentRun # Windows: gradlew.bat …
For other people, build the web app once and put the files on any web server:
./gradlew :composeApp:wasmJsBrowserDistribution
The files are in composeApp/build/dist/wasmJs/productionExecutable/ (about 13 MB: index.html, loadshift.js,
two .wasm files, fonts). They must be served over HTTP – opening index.html from the file system does not work.
A local test: cd composeApp/build/dist/wasmJs/productionExecutable && python3 -m http.server 8080, then open
http://localhost:8080. Any static host works (GitHub Pages, Netlify, Cloudflare Pages, a web server of your own);
the server should deliver .wasm files as application/wasm. This repository publishes it on GitHub Pages with the workflow .github/workflows/pages.yml.
./gradlew :composeApp:packageDmg # macOS, run on a Mac
gradlew.bat :composeApp:packageMsi # Windows, run on Windows
./gradlew :composeApp:packageDeb # Debian/Ubuntu, run on Linux
The installers are in composeApp/build/compose/binaries/main/. They are not signed: macOS asks for confirmation
on the first start (right-click → Open), Windows SmartScreen warns once.
For screenshots, tests and teaching: desktop ./gradlew :composeApp:run --args="-scenario 7 -play -ticks 40 -careful -lang de",
web index.html?scenario=7&play&ticks=40&careful&lang=de. scenario opens a scenario's briefing (101–103 are E2–E4),
play starts it, ticks runs that many 15-minute steps, careful plays like a careful player, solution plays the
solution, lang sets the language for this start, unlock opens every scenario for this start (stars still count) –
for teachers: ./build.sh desktop unlock, or index.html?unlock.
./gradlew :core:allTests # simulation tests on the JVM and in Wasm; the lesson report is in build/lesson-report.txt
build.sh (macOS and Linux) wraps the common tasks: ./build.sh ktest | web | serve | desktop.
| Path | Content |
|---|---|
core/ |
Kotlin Multiplatform module with the deterministic simulation (no UI) and its tests; LessonTest checks that every scenario teaches what it should |
composeApp/ |
Compose Multiplatform app: web (Wasm) and desktop (JVM) |
tools/ |
grid curves and fonts |
docs/CONCEPT.md |
game concept, model, decisions and sources |
Built with Kotlin 2.4 and Compose Multiplatform 1.12. The first version was written in Swift for iPad and Mac
(tag v0.3.0); the Kotlin version replaced it.
MIT, see LICENSE. The font Inter is under the SIL Open Font License 1.1 (tools/fonts/Inter-OFL.txt).