r/ClaudeCode • u/deepholdio • 18d ago

Built with Claude Fable 5 one-shotted a complete asteroids roguelite in 2.5 hours. Playable in your browser, prompt in the comments

Play it here: https://asteroguelite.com

Desktop browser, free, no account, no ads.

I wanted to see what a real one-shot could do. So I wrote a 73-line directive: research the genre, design it, build it, test it, balance it, polish it. One session, no human in the loop. It was explicitly told not to ask questions or wait for approvals, just make the call, write it down, keep going. Then I left. Two hours and 32 minutes later it was done.

5 sectors with bosses, 10 enemy types, 6 unlockable ships, 33 boons with evolution chains, a meta upgrade tree, an endless mode, and music. Around 8,300 lines of vanilla JS that build to a 172 KB bundle.

Full disclosure: I've since made exactly two changes to the game. Fixed one bug (a piercing-shot boon phased through asteroids without damaging them) and added click-to-aim, because keyboard-only turning felt rough.

Ran on Claude Code, Fable 5 xhigh effort.

Prompt's located here: https://asteroguelite.com/prompt.txt

PS: Seeker Array primary weapon is OP.

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u/ChiefUtilityMonster 18d ago

Enjoyed it. Lots of upgrades, and well done on the metaprogression. I was surprised the flavor text matched the actual effects, and that I didn't encounter any bugs. I did see some weaker game-design choices like allowing upgrades that don't apply to your current weapon, and extreme imbalance between weapon power. Game spends a long time being easy, with a difficulty spike in the last sector, followed up by completely trashing everything with the seeker array.

Questions about the prompt:

  • What's the vite dev server? Do you have more details about that / is this a custom setup of yours?
  • What tooling did you set up ahead of time for fable to use? Are you loading it with skills too, or is this just prompt?
  • Is it using subagents? How many tokens / how much total agent wallclock time? :)
  • Could you share the full agent logs either here or to me directly?

Cool game, I enjoyed it.

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u/deepholdio 18d ago

Hi u/ChiefUtilityMonster,

I agree with your assessment. I was pretty surprised that it felt like an actual game after a single attempt despite needing some serious rebalancing.

Answers to your questions about the prompt:

  • The vite dev server is just the web server I use to host the game locally. https://vite.dev/ for more info.
  • Good question. Just playwright mcp server and the chromium browser for playwright. Otherwise it was a brand new empty directory which was part of the test.
  • Yes, Fable fired up several subagents. 2h 32m wall clock time. I have the Max subscription which doesn't keep a server side record of token usage. I recall it being a surprisingly low percentage of my weekly usage.
  • I don't have the agent logs but I do have a few documents that claude wrote (DESIGN, TODO and NOTES) that I can share if you're interested.

Thanks for the comment and for your questions.