snatcher-port

A research project to reverse-engineer Konami's Snatcher (Sega CD, 1994) and build:

1. a clean-room PC port: a new engine that runs the original game data from your own disc;
2. a remaster that also supports the PC Engine CD (Japanese) version, a new English translation of it, and mixed text and voice language options;
3. a separate UE5 third-person reimagining prototype.

No game data is in this repository. Supply your own disc images in sega-cd-eng/ and pcengine-cd-jpn/. Both folders are gitignored.

Docs

• docs/PLAYING.md: how to build, run and share the playable Mac build (controls, options, saves)
• docs/STRATEGY.md: approach, phases, legal guardrails
• docs/DISC_LAYOUT.md: measured disc and format findings
• docs/SKILLS_AND_TOOLS.md: agent skills, tools, prior art
• docs/JOURNAL.md: RE log

Tools

# Sega CD: header + ISO9660 listing (add --extract extracted/scd to dump files locally)
python3 tools/disc_inspect.py "sega-cd-eng/Snatcher (Sega CD) (U)-redump.bin"

Ghidra project

tools/ghidra/setup_project.sh        # extracts code blobs -> extracted/code, builds ghidra/snatcher.gpr
ghidra                               # File > Open Project > ghidra/snatcher.gpr

Programs: scd_main_ip.bin (Main CPU, 0xFF0000) and scd_sub_sp.bin (Sub CPU: SP at 0x6000 plus SUBCODE.BIN at 0xD400). Re-running the script overwrites them. Once manual renaming starts in the GUI, stop re-running it.

Emulators (debuggers)

tools/emu/mame_debug.sh pce          # PC Engine CD, MAME debugger (needs System Card 3)
tools/emu/mame_debug.sh scd          # Sega CD, MAME debugger (needs BIOS mpr-15045b.bin in ~/mame/roms/segacd/)
open ~/Applications/Mesen.app        # Mesen 2: best PCE CD debugger

Build environment

nix develop            # compilers, SDL3, Ghidra, mingw-w64, ffmpeg (flake.nix)
mise run setup         # .venv with capstone
mise run extract       # carve code + overlay dump from your own disc (sega-cd-eng/)
mise run build         # translated native build -> engine/build/snatcher
mise run package:mac   # dist/Snatcher.app (personal: contains code translated from your disc, never share)
mise run package:mac-share  # dist/share/Snatcher-mac.zip (interpreter-only, shareable with players who own the game)
mise run package:windows
mise run run           # mouse = Konami Justifier (left trigger, right start); start without --justifier for pad only

Without Nix, the same tools via Homebrew work (brew install cmake sdl3 mingw-w64); on macOS use Apple clang (CC=/usr/bin/clang CXX=/usr/bin/clang++), not a Nix-profile gcc.