Claude reconstructs an FPS with compiler byte checks
Maurice Heumann reports months of Claude Code and Codex agents reconstructing an FPS, replacing unreliable progress signals with compiled function byte comparisons.
momo5502.com
Suggested prompt
Suggested prompt written by Agents In Use, not the source author. Replace bracketed inputs and review tool permissions first.
For an authorized binary reconstruction, inspect one assigned function and recover its source with the original toolchain. Compare compiled bytes against the reference while accounting for relocations, explain mismatches, and repeat before closing the tracking issue.
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See placements →Evidence at a glance
Sourced account- Source author
- Maurice Heumann
- Original account
- Read the source ↗
- Published
- 9 Oct 2026
- Source link checked
- 15 Oct 2026
- Reported result
- Heumann reports substantial visible progress followed by serious semantic errors, then adoption of function byte checks as a more reliable guide for reconstruction.
- Human involvement
- Human collaborators maintain the toolchain and instructions, inspect fidelity failures and define objective acceptance criteria. The game identity is withheld in the source.
A linked account supports attribution. It does not mean we independently reproduced its result.
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How the agent did it
- Assign translation units through GitHub issues and inspect original functions through IDA MCP.
- Run worker and reviewer agents with shared CI notifications and human-refined instructions.
- Identify semantic errors despite successful launches, menus and map loading.
Maurice Heumann describes a three-month effort to reconstruct a first-person shooter as readable C++. Claude Code and Codex agents used the official Hex-Rays IDA MCP integration to inspect binaries, GitHub issues to track translation units and Discord to exchange progress and receive CI failure notifications. Human collaborators maintained the environment and refined instructions.
The first month looked productive. The game launched, menus rendered and maps loaded, but closer inspection showed invented logic, incorrect signatures and structural changes that damaged fidelity. A separate reviewer agent did not reliably challenge the workers' explanations. Visible progress had concealed semantic errors.
The team then built an objective check around the original compiler. A script extracted compiled function bytes from reconstructed objects and compared them with the original executable, accounting for relocations. Agents could use a failed comparison to revise a function rather than defend a plausible reconstruction. The account describes a sustained workflow and useful failure evidence, not a verified release of the entire game. Heumann says modernization and portability were deferred to focus on original behavior.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Blog · Maurice Heumann
Frequently asked questions
Which reverse engineering tool did this project use?
The author says agents used the official Hex-Rays ida-mcp integration for most of the project.
Why were launch tests insufficient?
The game could launch and load maps while reconstructed signatures, structures and logic remained semantically wrong.
What changed the feedback loop?
The team compared compiled reconstructed function bytes against the original executable using the original compiler.
More details
Remaining steps
- Compile reconstructed functions and compare their bytes with the originals to guide further revisions.
About this account
Claude Code and Codex inspect binaries, manage assigned translation units, write reconstructed code and revise it using compilation and byte-comparison feedback.
Firsthand account opened and read. Original article visible date and metadata state October 9, 2026. Outcomes are author-reported and were not independently reproduced. Suggested prompt written by Agents In Use. Additional primary account replaces the generic Ghidra repository lead. The source uses IDA, and full-game completion is not asserted.
Credit: Maurice Heumann
Source published 9 Oct 2026
Source checked 15 Oct 2026
Tools and topics
Hex-Rays ida-mcp · GitHub CLI · Discord · Original compiler · Byte comparison script
Software · Claude Code with Codex CLI
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.