First Part II module. The cumulative reference adds a second engine (src/engine/puzzle: grid, lexer, parser) beside Part I's; nouns and properties are data in src/content/words.json, and the engine names only IS/AND/NOT/TEXT and the base rule TEXT IS PUSH. Rules are recompiled from the board on every change; rules() is a sorted set. Adds the M6 scenarios and tests (rows, columns, shared IS, AND distribution, stacked text, base rule), the HOT word as a data-only Expansion Drop, the lesson with the Part II bridge, and the Rust LevelDef shape in harness.md. Co-Authored-By: Claude Opus 5.5 <[email protected]>
Systemic Design Course
A free, hands-on course on systemic game design. You learn by rebuilding the rules machinery of two games, then extending it:
- Part I: Hearthstone (cards, zones, triggers, death phases, auras, text assembly)
- Part II: Baba Is You (rules as pushable text, parsing, movement, win/lose)
- Part III: SpellGrid, a small original game that combines both systems
Every module follows the same beats: Observe, Predict, Spec, Build, Name it, Expansion Drop, Further reading. The Expansion Drop is the test of your design: you add new content without touching the engine.
Two paths
- Designer path: read the lessons and scenarios, predict outcomes, and reason about the design.
- Builder path: also make the tests pass in your own engine.
Two tracks
Builder path exercises exist in Rust and TypeScript. Both tracks have identical test names, matching the scenarios in each module's scenarios.md.
Quick start
node --version # Node 24 for the course tooling
npm run test:tools # tooling tests
npm run check # test names agree across Rust, TS and scenarios
node tools/start-module.mjs 01 path/to/your/workspace
start-module copies a module's tests for your track (from your workspace's .course.json) and refuses to start a module if you have not yet taken the previous one. Module 00 uses the naive-engine/ project and is not started this way.
Other tools: tools/coupling-audit.mjs <workspace> (engine code must not name specific cards or nouns), tools/expansion-check.mjs <workspace> <baseRef> (an Expansion Drop must change content only), tools/verify-references.mjs [NN] (reference solutions pass the tests).
Licence
MIT, for both prose and code. See LICENSE. The course is and stays free.
Disclaimer
Not affiliated with Blizzard or Hempuli. See the disclaimer.