Isometric 3D foundation

A reusable, genre-agnostic foundation for grid-based 3D games rendered with an orthographic camera at an isometric angle. The world is real 3D Three.js geometry (not 2D sprites) — "isometric" here means the camera, not faked depth. Everything is driven by a tile grid: selection, movement, building, and pathfinding all speak in { tx, tz } tile coordinates, and a pair of pure helpers converts between tile / world / screen space.

This skill assumes the studio engine architecture (GameContext + GameSystems registry, imperative Three.js, React HUD via StateListener). See shipshit-engine for that shape. Read the canonical FPS proof for the system pattern: games/scourge-survivors/src/game/context.ts, games/scourge-survivors/src/game/render/RenderSystem.ts, games/scourge-survivors/src/game/data/maps.ts.

The FPS uses a PerspectiveCamera + PointerLockControls; an iso game swaps both out for an OrthographicCamera + a custom IsoCameraSystem. Everything else (context-as-world, systems-call-siblings-via-this.sys, data-driven content) is identical.