I built an open-world game with Claude Opus 5.5 and Godot, and the whole thing comes down to one rule.

Never ask for "An open world".
Ask for one feature, play it, then ask for the next.

What came out: a mountain map, a glider that actually flies, a ruined tower, enemies that fight back, and a character that is way too happy about all of it.

The order:

Step 1 -> Opus 5.5 in Claude Code, opened inside the Godot project itself.

Step 2 -> Greybox the terrain and the camera first, zero art.

Step 3 -> One mechanic per prompt: walking, then the glider, then combat. Each one played until it feels right.

Step 4 -> Reference images in the game's style from Codex/Astra, and every prompt that works saved as JSON, so the style never drifts.

Step 5 -> Big models in Tripo P2 from those refs, small props in Blender, textured in Tripo with the same refs.

Step 6 -> Animation in Cascadeur, then light, fog and sound at the very end.

Step 7 -> Every VFX and shader written down in Obsidian, so the look holds from the first scene to the last.

The split:

Opus 5.5: most of the code, scene setup, cleanup.
Codex/Astra: references.
Tripo P2 + Blender: every model.
Godot: custom tools, headless scripts, the game itself.
Me: play it and decide what stays.

Commit after every step that works.
One JSON file of good prompts is why every rock, tower and enemy looks like it belongs in the same world.