Decompile a classic game to byte-exact C source with LLMs
A developer used LLMs to decompile Civilization 1 into reconstructed C that builds with the original Microsoft C toolchain, along with a technical book about the process.
Source
crc32 on Hacker News · 2026-10-20 · Project link
Written in our own words. Credit to the original author. Link checked 2026-10-22.
What they did
A developer used LLMs to decompile Civilization 1 into reconstructed C that builds with the original Microsoft C toolchain, along with a technical book about the process.
Result (as claimed)
A byte-for-byte match with the original executable apart from a 4-byte post-link patch.
Tools they used
Cost: Pricing depends on the tools you pick; check each official pricing page.
Set it up
Gather your sources
Collect the papers, notes, links or files you want to work from in one place.
Load them into the tool
Open LLM, Microsoft C and add your sources. Keep the original files so you can check claims later.
Ask focused questions
Ask for summaries, comparisons or connections with citations to the source passages.
Verify and save
Spot check claims against the sources, then save the output as notes you can reuse.
Copy the full setup prompt
Paste into your agent and it will walk you through the setup, asking before anything that sends, posts or spends.
You are helping me set up this AI use case end to end in Claude Code. Goal: Decompile a classic game to byte-exact C source with LLMs What the original author did: A developer used LLMs to decompile Civilization 1 into reconstructed C that builds with the original Microsoft C toolchain, along with a technical book about the process. Reported result (as claimed by the author): A byte-for-byte match with the original executable apart from a 4-byte post-link patch. Source: https://news.ycombinator.com/item?id=50163253 Tools they used: LLM, Microsoft C Category: Research & learning Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
You are helping me set up this AI use case end to end in Codex. Goal: Decompile a classic game to byte-exact C source with LLMs What the original author did: A developer used LLMs to decompile Civilization 1 into reconstructed C that builds with the original Microsoft C toolchain, along with a technical book about the process. Reported result (as claimed by the author): A byte-for-byte match with the original executable apart from a 4-byte post-link patch. Source: https://news.ycombinator.com/item?id=50163253 Tools they used: LLM, Microsoft C Category: Research & learning Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
You are helping me set up this AI use case end to end in Grok Bot. Goal: Decompile a classic game to byte-exact C source with LLMs What the original author did: A developer used LLMs to decompile Civilization 1 into reconstructed C that builds with the original Microsoft C toolchain, along with a technical book about the process. Reported result (as claimed by the author): A byte-for-byte match with the original executable apart from a 4-byte post-link patch. Source: https://news.ycombinator.com/item?id=50163253 Tools they used: LLM, Microsoft C Category: Research & learning Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
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Guides for this use case
How to mod and reverse engineer games with AI · How to vibe code a game with AI
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