Pull one game's movement physics into another with Claude Code and REA
A modder pointed the free REA reverse-engineering tool and Opus 5.5 at the 1991 Sonic binary. It found the six constants behind Sonic's feel, then located Elden Ring's player movement and wrote a controller with spin dash and rings.
Source
@Capslock404 on X · 2026-10-15
Written in our own words. Credit to the original author. Link checked 2026-10-22.
What they did
A modder pointed the free REA reverse-engineering tool and Opus 5.5 at the 1991 Sonic binary. It found the six constants behind Sonic's feel, then located Elden Ring's player movement and wrote a controller with spin dash and rings.
Result (as claimed)
About 40 minutes from question to Sonic spin-dashing in Elden Ring, with no Sega code copied.
Tools they used
Cost: Claude Code: from $17/mo; Claude Opus 5.5: from $4 in / $20 out per 1M tokens.
Set it up
Write a one-page brief
Describe the app in plain words: who it is for, the 3 core screens or actions, and what "done" looks like.
Start the project with your agent
Open Claude Code and paste the brief. Ask it to propose a stack and a file plan before writing code.
Build one slice at a time
Ship the smallest working flow first, run it, then add features one by one. Commit after each working step.
Test it like a user
Click through on desktop and phone. Ask the agent to add basic tests and fix anything that breaks.
Check security and ship
Keep keys in environment variables, check auth and database rules, then deploy and share the link.
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: Pull one game's movement physics into another with Claude Code and REA What the original author did: A modder pointed the free REA reverse-engineering tool and Opus 5.5 at the 1991 Sonic binary. It found the six constants behind Sonic's feel, then located Elden Ring's player movement and wrote a controller with spin dash and rings. Reported result (as claimed by the author): About 40 minutes from question to Sonic spin-dashing in Elden Ring, with no Sega code copied. Source: https://x.com/Capslock404/status/2110648710606557644 Tools they used: Claude Code, Claude Opus 5.5, REA, Ghidra Category: Vibe coding & apps 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: Pull one game's movement physics into another with Claude Code and REA What the original author did: A modder pointed the free REA reverse-engineering tool and Opus 5.5 at the 1991 Sonic binary. It found the six constants behind Sonic's feel, then located Elden Ring's player movement and wrote a controller with spin dash and rings. Reported result (as claimed by the author): About 40 minutes from question to Sonic spin-dashing in Elden Ring, with no Sega code copied. Source: https://x.com/Capslock404/status/2110648710606557644 Tools they used: Claude Code, Claude Opus 5.5, REA, Ghidra Category: Vibe coding & apps 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: Pull one game's movement physics into another with Claude Code and REA What the original author did: A modder pointed the free REA reverse-engineering tool and Opus 5.5 at the 1991 Sonic binary. It found the six constants behind Sonic's feel, then located Elden Ring's player movement and wrote a controller with spin dash and rings. Reported result (as claimed by the author): About 40 minutes from question to Sonic spin-dashing in Elden Ring, with no Sega code copied. Source: https://x.com/Capslock404/status/2110648710606557644 Tools they used: Claude Code, Claude Opus 5.5, REA, Ghidra Category: Vibe coding & apps 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 an app with Claude Code · How to reverse-engineer and revive old devices with AI · How to vibe code a game with AI
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