BABEL — prototype implementation

BABEL is a digital-first solo / 2–4 leader cooperative-competitive board game.

Humanity is building the Tower of Babel to reach Heaven and kill a tyrannical God. Everyone must keep the project alive; if Babel reaches Heaven, the surviving leader with the most Prestige wins the glory.

Start here

1. docs/GDD.md — canonical rules and design source of truth.
2. docs/RULES_QUICK_REFERENCE.md — compact implementation reference.
3. AGENT_HANDOFF.md — what to build, what not to redesign, and prototype acceptance criteria.
4. TECH_ARCHITECTURE.md — recommended code boundaries and framework guidance.
5. IMPLEMENTATION_PLAN.md — milestone order.
6. ART_DIRECTION.md — visual/tone brief.
7. docs/FINAL_BALANCE_PASS_2026-09-15.md and docs/MODEL_NOTES.md — modelling evidence and tuning context.
8. docs/NEXT_WORK_TRIAGE.md — current deferred-work order and scope notes.

Canon versus tuning

Rules explicitly marked TUNEABLE in the GDD are balance values. Do not casually change structural rules during the first implementation milestone. If a rule blocks implementation or produces an obvious contradiction, document it rather than silently redesigning it.

The live default is canon v0.6: rolled Heaven uses the adopted player-count cadence and Hosts route on dry river banks from the fixed Beacon start. V05_RULES and V04_RULES remain available as frozen rulesets for historical comparisons.

First playable goal

A complete local hot-seat game for 2–4 Leaders (solo controls two Leaders) with:

• square tile placement and river legality;
• feature detection and resource payouts;
• harvesting buildings and occupation;
• Babel construction and permanent stage escalation;
• Beacons, Ophanim Hosts and Seraphs;
• shortest-path Heavenly movement;
• Army dice, Towers and Walls;
• Prestige;
• the compact Scheme and escalating Confusion decks;
• win/loss states;
• a transparent game/event log.

Visual polish, networking, accounts, characters, expanded content and animation are explicitly deferred until the core game is fun.

Architecture direction

Use TypeScript + React + Vite + Vitest, with a pure deterministic game-core separated from rendering. Spike boardgame.io briefly as an orchestration/multiplayer candidate, but do not put core rules inside framework-specific callbacks.

The art/tone target is a cheerful, handmade civic project to murder God, besieged by horrifying-but-cute celestial geometry. See ART_DIRECTION.md.

Repository layout

packages/game-core   pure deterministic rules; no framework imports
packages/game-data   TUNEABLE values: terrain weights, player-count scaling
apps/web             hot-seat UI, drives game-core directly
spike/boardgame-io   maintained multiplayer spike (see ADR-001)

npm install
npm test          # vitest, all packages and the spike
npm run typecheck # packages, web app and spike
npm run verify    # typecheck + tests
npm run dev       # hot-seat app

Progress

• Milestone 0 — framework spike. Complete. See docs/ADR-001-framework.md for the orchestration decision.
• Milestone 1 — spatial economy. Complete. Square grid, five terrain types, river shapes with free rotation and symmetric edge matching, connected-feature detection, adjacency payouts with occupation suppression, 2–4 hot-seat Leaders, and a board UI that highlights legal squares and projects the payout before you commit.
• Milestone 2 — industry, Babel and Prestige. Complete. Sawmill, Farmstead, Brickworks and Mine with per-feature ownership; the foreign expansion trigger paying every foreign owner plus a single +1 to the placer; Babel's growing stack with permanent Stage escalation and shared victory; Barter; Prestige for buildings and Babel pieces.
• Milestone 3 — Heaven. Complete. Beacons sited collectively on legal frontier tiles; Ophanim Hosts and Stage-III Seraphs; shortest-path movement that rivers permanently reshape; Babel strikes and the two-step Foundation breach; Army dice, Muster, and Attack with hit assignment. The game can now be won or lost.
• Milestone 4 — defensive geography. Complete. Towers contributing one targeted support die per occupied feature during any Leader's Attack, and Walls as temporary barricades that a Host destroys by spending its movement.
• Milestone 5 — the compact card layer. Complete. The three Schemes with hidden hands, and the six Confusion effects with the deck growing as Babel escalates. Canon v0.1 is now fully playable.
• Canon v0.5 cadence adoption. Complete. Heaven's Stage I/II/III arrival cycles now scale by the 2/3/4-Leader table size from the scheduled first Beacon round, while V04_RULES keeps historical fixed-arrival comparisons reproducible.
• Canon v0.6 bank-routing adoption. Complete. Hosts use the adopted dry-bank route from the fixed Beacon start; V05_RULES freezes the preceding canon for historical controls and experiment replay.
• Milestone 6 — playtest instrumentation. Next: per-game telemetry and deterministic replay from seed plus command log.

Interpretations of under-specified canon are recorded in docs/RULES_DECISIONS.md.

What is not implemented yet

All seven actions are live. The deferred content in GDD §23 — character powers, Titles, roads, trading, more cards or enemies — stays deferred until human play says the game needs it.