ImHex to Reverse Engineer FEZ Save File Format
Original: Reverse Engineering Unknown File Formats with ImHex
Why This Matters
Demonstrates a reproducible, tool-driven methodology for binary format reverse engineering using open-source tooling.
ImHex developer WerWolv published a detailed tutorial (Aug 27, 2026) on reverse engineering FEZ's binary save file format using ImHex and its Pattern Language, walking through decompilation, hex analysis, and full format documentation.
ImHex developer WerWolv published a step-by-step guide on reverse engineering the custom binary save file format used by the 2012 game FEZ. The tutorial covers the full workflow: locating the save file (e.g., `/home/user/.local/share/FEZ/SaveSlot2` on Linux), opening it in ImHex, decompiling the game's source code to identify reader/writer functions, and progressively writing a Pattern Language definition that fully describes the file structure. Key topics include parsing primitive types, strings with length prefixes, lists, enums, and subtypes. The guide notes that some features used require ImHex Nightly (beyond v1.38.1). The post is intended as a repeatable methodology for anyone facing unknown binary formats, not just FEZ-specific content. ImHex is free, open-source, and cross-platform, with a browser-based version also available. The author notes the save file is uncompressed and unencrypted, making it accessible for static analysis. A spoiler warning is included, as reverse-engineered data reveals endgame secrets.