references/level-design.md

# Level design and flow

Define one intended learning objective and one game-mechanic test per level. Block out first. Include spawn, signposting, safe introduction, challenge, optional reward, completion/failure and restart path.

2D: verify jump gap and wall height against actual movement constants, tile collision, camera bounds and collectible reachability.
3D: verify world scale, navigation path, occlusion, camera clipping, slopes, collider dimensions and checkpoints.

Use completion walkthroughs from start to finish, including failure states and optional routes. Do not populate empty worlds with scenery while the game loop is missing.