Engine Agent Kits: Godot 4, Unity 6 and Unreal 5 rules files, editor bridges and build loops for coding agents

Run the headless check and the test and build commands in ENGINE.md.
Fix everything that fails without adding features. Report what you changed.

No feature work until the build is green.

Write a test scene that loads [level], runs this input sequence and saves player position every half second, a screenshot at the end and a 12-frame sheet.
Review the outputs against [expected behavior].

Numbers beat pictures for physics bugs.

# Engine Agent Kits: Godot 4, Unity 6 and Unreal 5 rules files, editor bridges and build loops for coding agents

A PaperChaseWebb pack, version 1.0. Written for Claude Code, Codex and Cursor, and plain Markdown, so the rules files, trap tables, build commands and prompts work with any coding agent that can run a terminal.

Game engines are where coding agents stumble hardest. Training data mixes engine versions, so the agent writes Godot 3 code in a Godot 4 project. Scenes, prefabs and blueprints are binary or fragile text the agent should not hand-edit. And the agent cannot see the game, so it reports "the jump feels great" about a character that falls through the floor. This pack is one kit per engine: a rules file to paste, a trap table of the mistakes agents make most, the terminal commands that let the agent build and test without you clicking, ways to give it eyes, and a work loop that keeps each session small and playable.

It goes further than the engine notes in our Game Dev Agents pack, which cover first steps. It is built from public build reports by solo developers and jam teams who made games with coding agents in Godot, Unity and Unreal, plus our own setups. Sources are credited by link in the Sources section.

## What is inside

| Section | What it is for |
|---|---|
| 1. Why engines break agents | Version drift, fragile files and no eyes |
| 2. Engine-neutral setup | ENGINE.md, a milestone plan and the one-milestone session |
| 3. Godot 4 kit | Rules file, a 24-row Godot 3 to 4 trap table, headless checks and web export |
| 4. Unity 6 kit | Rules file, meta file rules, batchmode builds and tests, editor scripts |
| 5. Unreal 5 kit | Rules file, terminal builds, C++ first, editor bridges and asset licenses |
| 6. Giving the agent eyes | Screenshots, frame sheets, scene queries and measurements |
| 7. Asset pipelines | Generated 3D, code-only art and premade packs with a license ledger |
| 8. Session economics | Route easy work to small models, hand off cleanly, keep a research vault |
| 9. The overnight loop | A dated work order, a build window and stop rules |
| 10. Fun is your job | Playtesting what an agent cannot judge |
| 11. Prompts | 14 prompts across all three engines |
| 12. Sources | What we used and how we used it |