Gaia Engine: steampunk myth FPS

A shooter game Ethan Hann built with Claude Opus 5.5. Copy the exact prompt free.

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by Ethan HannFreeOpus 5.5 game prompts

Ethan Hann built this with Claude Opus 5.5 and shared the full prompt on GitHub; it is quoted below word for word. A steampunk first-person shooter built on Greek myth, from a one-file game brief. The creator ran Opus 5.5 at High effort and steered it a little during the build. Kick-off prompt; the creator steered a little during the build.

The prompt

You are an experienced game developer that is an expert at 3d game design. You ship tight, bug-free code.

Your goal is a 3d game with the follow idea:
Genre: FPS
Rule: You Are The World
Setting: Steampunk
Theme: Myth

STANDING RULES:
1) The game must have a goal and an end state.
2) The game should have a small tutorial at start explaining the mechanics.
3) You must use Three.js for 3d rendering.
4) One contained HTML file.
5) No subagents and no workflows.

I will not describe the game any more than that. You will continue until a complete, playable game has been produced. Do not surface design questions to me and do not ask me anything. You make the decisions. You may use any skill needed to help with the design and implementation.

Prompt by Ethan Hann, quoted word for word from their GitHub repository. Model as stated by the creator; your result will differ.

What’s inside

  1. Copy the prompt below, or download it as a SKILL.md
  2. Paste it into Claude Opus 5.5, ideally in Claude Code so it can write, run and test the game
  3. Swap in your own theme, characters or rules where the prompt names theirs
  4. Play it, then ask for fixes and polish in plain words

What you’ll bring

  • Claude Opus 5.5 (Claude Code, or a Claude chat for single-file HTML games)
  • A browser to play the result
  • Your own twist on the idea, if you want one

What you’ll get

  • A playable browser game in the spirit of the one above, written by Claude
  • The code, which you can keep editing

Perfect for

  • Anyone who wants to make a game without coding
  • Developers testing what Opus 5.5 can build
  • Teachers and parents making a game with kids

Also found as

opus 5.5 game prompt · claude game prompt · one shot game prompt · shooter · gaia engine: steampunk myth fps

Questions

What is Gaia Engine: steampunk myth FPS?

Gaia Engine: steampunk myth FPS is a shooter game that Ethan Hann built with Claude Opus 5.5. This page quotes the prompt they shared, word for word.

Who made it, and where was the prompt shared?

Ethan Hann made it and shared the prompt on GitHub: https://github.com/ethan-hann/claude-fun#gaia-engine. You can find more from them at https://github.com/ethan-hann/claude-fun.

How do I use the prompt?

1. Copy the prompt below, or download it as a SKILL.md. 2. Paste it into Claude Opus 5.5, ideally in Claude Code so it can write, run and test the game. 3. Swap in your own theme, characters or rules where the prompt names theirs. 4. Play it, then ask for fixes and polish in plain words.

Is it free?

Yes. Copying the prompt and downloading the SKILL.md costs nothing on Omo. You run it with your own access to Claude Opus 5.5.

The video and the prompt belong to Ethan Hann. Omo lists them free, with credit and a link to the original post. Creators can ask us to remove a listing at omo.space/support.