Project Sylpheed: Arc of Deception — Reborn

A clean-room, open-source reimplementation of Project Sylpheed: Arc of Deception (Xbox 360, 2006).

Built with Rust and the Bevy game engine. Runs natively on Windows, macOS, and Linux, and in the browser via WebAssembly.

Legal note: This project contains no original game code or assets. You must own a legitimate copy of Project Sylpheed to use this engine. Assets remain the intellectual property of SETA Corporation / Square Enix.

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Current Status: Milestone 1 — Asset Explorer

• XISO disc image reading via xdvdfs
• Xbox 360 texture de-tiling (Morton / Z-order)
• XPR2 texture container parsing
• Bevy custom AssetLoader for .xpr textures
• Orbit camera viewer
• CLI tools: extract, list, sniff, texture info, texture export
• GitHub Actions CI (Windows + macOS + Linux + WASM)
• WASM / web build target
• Mesh format (reverse engineering in progress)
• Audio format (XMA → PCM pipeline)
• Mission data format

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Repository Structure

sylpheed-reborn/
└── sylpheed-viewer/        ← Milestone 1: asset explorer (Rust/Bevy workspace)
    ├── Cargo.toml          ← Workspace root
    ├── crates/
    │   ├── sylpheed-formats/   # Format parsers — no Bevy dependency
    │   │   ├── xiso.rs         # XISO / XDVDFS disc image reader
    │   │   ├── texture.rs      # XPR2 container + DXT de-tiling (Morton)
    │   │   ├── vfs.rs          # Virtual filesystem + magic-byte sniffer
    │   │   ├── mesh.rs         # Mesh parser (stub — RE in progress)
    │   │   └── audio.rs        # Audio parser (stub — XMA TODO)
    │   │
    │   ├── sylpheed-viewer/    # Bevy application
    │   │   ├── lib.rs          # App setup + WASM entry point
    │   │   ├── main.rs         # Native binary entry point
    │   │   ├── asset_loader.rs # Custom Bevy AssetLoaders
    │   │   ├── camera.rs       # Orbit camera (LMB orbit, RMB pan, scroll zoom)
    │   │   └── ui.rs           # egui file browser + RE notes panel
    │   │
    │   └── sylpheed-cli/       # Command-line tools
    │       └── main.rs         # extract / list / sniff / texture info commands
    │
    ├── assets/             ← Extracted game files (gitignored)
    ├── .github/workflows/
    │   └── ci.yml          # CI: Windows + macOS + Linux + WASM
    ├── Trunk.toml          # WASM build configuration
    └── justfile            # All build recipes

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Getting Started

Prerequisites

# Install Rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# Install just (task runner)
cargo install just

# For web builds only
cargo install trunk
rustup target add wasm32-unknown-unknown

Linux — Bevy system dependencies

sudo apt-get install -y \
  libasound2-dev libudev-dev libwayland-dev \
  libxkbcommon-dev libx11-dev libxi-dev pkg-config

Step 1 — Extract your disc

cd sylpheed-viewer

# Extract using the CLI tool
just extract /path/to/project_sylpheed.iso

# Or manually with xdvdfs
cargo install xdvdfs-cli
xdvdfs unpack project_sylpheed.iso ./assets/

Step 2 — Run the viewer

cd sylpheed-viewer

just run          # Native viewer
just web          # WASM dev server → http://localhost:8080

The asset viewer opens an orbit camera scene. Use the left panel to browse extracted game files. Click a .xpr file to preview it as a texture.

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Build Commands

All commands run from the sylpheed-viewer/ directory.

just run              # Run the native viewer (debug)
just run-dev          # Run with hot-reloading
just build-native     # Build native release binary
just web              # WASM dev server at localhost:8080
just build-web        # WASM release build → ./dist/

just extract game.iso # Extract an ISO to ./assets/
just sniff            # Identify file formats in ./assets/
just sniff-unknown    # Show only unrecognised formats (RE focus)

just test             # Run all tests
just ci               # Full CI: fmt + lint + test + WASM check

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Technology Stack

Layer	Choice	Reason
Language	Rust	Memory safety, performance, cross-platform
Game engine	Bevy 0.15	ECS-first, WASM-native, data-driven
XISO reading	xdvdfs	Pure Rust, reads Xbox 360 disc images
Binary parsing	binrw	Derive-macro based, ideal for RE work
Web bundler	Trunk	Bevy's standard WASM build tool
CLI	clap	Asset extraction and inspection tools
Debug UI	bevy_egui	In-viewer asset browser and RE notes panel

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Key Architectural Decisions

sylpheed-formats has zero Bevy dependency. All binary format parsers live here and are testable with plain cargo test. Bevy integration is a thin layer on top in sylpheed-viewer.

WASM is a first-class target. XISO reading is gated behind #[cfg(not(target_arch = "wasm32"))] since the browser can't read local files. On the web, assets must be pre-extracted and served over HTTP.

Modding is designed in from the start. The virtual filesystem (vfs.rs) is the single choke point for all asset reads — a mod loader only needs to intercept that one layer to override any file.

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Reverse Engineering Notes

Known file formats

Path pattern	Format	Status	Notes
*.XPR, *.XPR2	XPR2 texture	✅ Parsing	DXT1/3/5, DXN, Morton de-tiling done
DEFAULT.XEX	Xbox EXE 2	🔬 Study	Main executable — load in Ghidra (PPC BE)
*.XWB, *.XSB	XACT audio	⏳ TODO	Wave/sound banks; audio is XMA codec
*.pak, *.p00	SETA archive	⏳ Unknown	Paired header/data format
mesh files	Unknown	⏳ TODO	Run just sniff-unknown to find candidates

RE workflow

# 1. Extract and map the disc
just extract game.iso
just sniff-unknown   # shows hex magic bytes of unknown files

# 2. Hex-inspect candidates
#    Groups of 12 bytes at offsets: likely f32 XYZ vertices
#    Groups of 6 bytes:             likely u16 triangle indices

# 3. Cross-reference in Ghidra
#    Load DEFAULT.XEX with PowerPC Big-Endian processor
#    Search string refs to file extensions → find load functions

# 4. Implement parser
#    Add binrw #[derive(BinRead)] struct in sylpheed-formats/src/mesh.rs
#    cargo test -p sylpheed-formats

Next steps (Milestone 2)

1. Mesh format — fingerprint with sniff-unknown, implement mesh.rs
2. Audio — parse XWB headers, batch-convert XMA to WAV via ffmpeg
3. Mission data — format unknown; starts after mesh/texture loading works
4. Flight model — document by playing the original; implement as Bevy system

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Constraints

1. Never copy decompiled or disassembled game code — reimplement behavior through observation only.
2. Assets stay gitignored — assets/ and *.iso are excluded. Never commit game files.
3. Keep sylpheed-formats Bevy-free — parsers must be testable without a GPU.
4. WASM must always compile — CI enforces cargo check --target wasm32-unknown-unknown.
5. justfile is the source of truth for build commands — add new recipes there.

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Milestone Roadmap

Milestone	Goal	Status
1	Asset Explorer	🚧 In Progress
2	Flying Tech Demo	⏳ Planned
3	Combat Prototype	⏳ Planned
4	Mission 1 Playable	⏳ Planned
5	Full Game (all 16 missions)	⏳ Planned
6	Mod SDK	⏳ Planned

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Useful References

• xdvdfs — XISO disc image reader (used in this project)
• Xenia emulator — GPU/API reference (cloned at ../../xenia-canary/)
• xboxdevwiki — Xbox 360 hardware documentation
• binrw docs — binary format parsing framework
• Free60 Project — open Xbox 360 hardware docs