A 45° isometric two-player online co-op action RPG built on three.js. Worlds are seeded and endless; terrain features are laid out in whole metres on a 1 m grid and built from 25 cm voxels. Steam integration targets appid 480 (Spacewar) during development.
Pre-production. There is no engine and nothing to play yet. What exists is the seeded terrain generator and the concept plate that locks generation rules, biomes and the gear lattice.
docs/DECISIONS.md — the design decision record. The authority on what the game is.src/gen/ — the terrain generator. Plain ES modules, no DOM and no three.js; it runs in
Node, in a worker and in the browser alike. See src/README.md.docs/concept/index.html — concept plate, published at
https://claude.ai/code/artifact/10034b02-a25d-4f5b-ab04-cea2076ceee8 — or open it in a browser. The hero diorama and all
six biome plates are live three.js renders produced by the same seeded generator, not
artwork. Type a seed and press Generate to produce a different world.| Rule | Value |
|---|---|
| Chunk | 32 × 32 m footprint, 16 m ceiling — 128 × 128 × 64 voxels |
| Feature grid | 1 m. Every feature dimension is a whole number of metres |
| Voxel | 25 cm. Used for surface detail, palette dithering and silhouette only |
| Detail pass | ±2 voxels (±0.5 m), the only sub-metre operation |
| Seeding | One string seed drives climate, heightfield, features and props, so co-op partners generate identical terrain without transferring it |
| Columns | Stored as runs of solid spans, not a single height — caves, tunnels and true undercuts are the same case |
Feature ranges: canyons 3–5 m wide and 3–4 m deep; rivers 1–4 m wide with the bed 1 m below the bank; hills 1–3 m; arcs 4–6 m span and 3–5 m rise; columns 2–4 m tall; overhangs undercut a rim by 1–2 m, and paired across a canyon they leave a 2–3 m gap a player can clear. Waterfalls are emitted wherever a watercourse steps down a metre; basins fill as ponds at 1.25 m. Grass (0.3–0.9 m) and water are never voxelised — both are shader-driven, with wind, a trample radius around every character, and flow-advected foam.
The movement budget is the contract between the generator and the character controller: step up 1 m, vault 2 m, jump a 2.5 m gap, survive a 6 m drop, wade 0.75 m (river beds sit exactly there), swim anything deeper, and magma is lethal and impassable. Trails are routed with A* over those costs and the ground is then graded under them so no step along a route exceeds a metre; crossings are placed only where a route actually meets water, with both banks dry. When a world has water that no route happened to cross, the generator finds the narrowest ford — a short water run with dry, level banks — and takes the route over it, so water-bearing worlds always get a crossing and dry ones never get a pointless one. A reach pass floods from the spawn under the same rules and marks what it cannot get to — a generator test, not a debug view. Arm Reach on the plate to see it.
Nine systems drive the generator rather than a list of special cases: span columns (a pseudo-3D field cuts caves before rims undercut them), a flow field and water table (downhill vector per cell; hollows flood until they spill), an erosion pass (talus at cliff feet, banks cut back above water), trails (routes drawn between sites before anything is built), an accumulation pass (snow and ash settle on up-facing surfaces by biome and slope), one wind field (shared by grass and water), destructible terrain (carve voxels live — arm Carve on the plate and click), chunk-scale landmarks (an obelisk, hive tree, wrecked machine or standing stones on the highest flat ground, chosen to suit the biome), and routing and reach (above).
Clutter is voxelised on the same lattice and derived from the terrain where possible: scree falls out of every 2 m drop, and bushes, stumps, fallen trunks, fences, lamp posts, ruined walls, pillars, huts and deck bridges are placed by terrain rules rather than scattered. Two points of interest per world — a ruin and a holding — are sited only on ground flat enough to have been built on.
Temperature and moisture are sampled as two low-frequency fields. Each of four biomes sits at a point in that space and every column is a weighted blend of them, so palettes, densities and feature sets cross-fade rather than switch.
Meadowlands · Redrock Mesa · Cloudpine Highlands · Thornwood
Over the climate, four scars — the damage the old weapons did — are painted as a separate overlay field, so a scar cuts across whatever biomes lie under it and never quite hides them.
Ashfall Barrens · Rimewaste · Sporeverge · Glasslands
Weapons and armour are frames: base stats, an affinity, and a cluster of hexagonal sockets. Frames never level up. Seven of the eight are symbiotic rather than historical: longblade (the control case), splice gauntlet, hookline spool, emberpot censer, brood sling, tuning stake, lodestone flail, root bulwark. Seating two modules of a frame’s own discipline wakes its trait.
Nine modules across three disciplines: tech (arc capacitor, servo edge, kinetic battery), magic (frostbind, emberweft, echo rune), biological (sporeling, bonegraft, vinelash).
Modules fuse only when their hexes share an edge, so socket layout is part of the build. Same discipline pairs amplify a stat and take a drawback; cross-discipline pairs bend behaviour into something neither module does alone.