20 days building a photoreal Unity island with Claude Code: self-checking agent workflow detailed

imlo2 · reddit · 2026-10-25

A developer shares part 2 of building a North Atlantic island in Unity with Claude Code, based on real Lofoten, Norway elevation data (4x5km, 1000m peak), aiming at a generalized procedural system where nearly everything — rocks, moss, forests, bird flocks — is placed by rules reading height and water data.

Division of labor: the human sets direction, picks algorithms and references, reviews visually and tunes parameters; Claude Code writes code, shaders and tools, then tests and benchmarks itself.

10-day progress: custom tree generator (root plates, branch growth, texture blending), reworked ground cover, LOD and shadow-unification improvements, finer clouds plus a storm type with lightning, and a basic wildlife system (gulls, geese, eiders, ravens, dragonflies).

Claude's self-checking workflow (the most valuable part):

Renders normals, motion, materials and lighting terms and reads the numbers instead of eyeballing; multiple mechanisms trap blind spots.
Changes are only kept after fixed-camera before/after renders with frame-time measurement.
Dead-end experiments get parked; it researches papers and shipped-game talks first, and profiles the GPU when frame times grow.
Concrete bug: sea slightly pulsing on camera movement — Claude measured the delta between a slow pan and predicted motion vectors, diagnosed incorrect motion vector generation, and fixed it.

Runs above 60fps at 1440p on an RTX 3090.

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20 days building a photoreal Unity island with Claude Code: self-checking agent workflow detailed

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