Light tells the scene's story. The un-opinionated default — one white directional at noon over flat gray ambient — is why agent-built games look like documents. Every 3D scene built under these floors ...

Material — the paved default: Sprites/Default (or URP particle-unlit explicitly set to Transparent) tinted from the palette; the failure table below has the two traps. Additive/glow sparingly and only ...