OpenConquer

A native macOS reimplementation of the classic 1995 Westwood real-time strategy game Command & Conquer: Tiberian Dawn, written in Swift + SDL2.

⚠️ Unofficial fan project. OpenConquer is not affiliated with, endorsed by, or sponsored by Electronic Arts. "Command & Conquer" and "Tiberian Dawn" are trademarks of Electronic Arts Inc. No game assets are included. You must own the Command & Conquer Remastered Collection and supply your own assets (see Assets).

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Screenshots

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Why this exists

There is no polished, native, faithful way to play the original Tiberian Dawn on a Mac:

• The C&C Remastered Collection is Windows-only (runs on Mac only via Wine/CrossOver/Parallels).
• OpenRA is native and excellent, but deliberately reinterprets the game on a modernized engine — it isn't original parity.
• Vanilla-Conquer (EA's GPL source, faithful) builds on Mac but is a niche, build-it-yourself experience.

OpenConquer aims at the empty square: native Mac · faithful simulation · modern presentation · fully moddable.

Design principle: faithful simulation, modern presentation, data-driven.

• Faithful simulation — mechanics and behaviors match the original where it counts (cross-checked against EA's released C++).
• Modern presentation — arbitrary window size, smooth zoom, and optional HD art from the Remastered Collection.
• Data-driven — units, rules, and missions live in data, so the game is configurable (classic vs. enhanced rulesets) and moddable.

See docs/VISION.md and docs/ROADMAP.md.

Status

Early but very playable: GDI and Nod campaign missions, AI, pathfinding, fog of war, economy/harvesting, combat, superweapons, save/load, and both classic-SHP and remastered-HD rendering. Expect rough edges and missing features — this is a work in progress and contributions are welcome.

Requirements

• macOS 13+
• SDL2 — brew install sdl2 pkg-config
• Swift toolchain (Xcode or the swift.org toolchain; the package targets swift-tools 5.9)
• A legally-owned copy of the C&C Remastered Collection (for game assets)

Assets

OpenConquer ships no game data — you extract it from your own legally-owned copy of the Remastered Collection.

One-command install (recommended)

pip3 install Pillow            # one-time: needed for HD sprite extraction
./install-assets.sh /path/to/CnCRemastered

install-assets.sh is a guided installer that does the whole setup in one shot: it installs the classic MIX archives, then extracts the classic audio and all the remastered HD art (sprites, cursors, sidebar meters) and audio. Point it at your Remastered Collection install — either the folder that contains Data/ or the Data/ folder itself. If you omit the path it probes the usual macOS locations (Steam, ~/CnCRemastered, /Applications, EA app).

It's safe to re-run, and it never downloads or bundles game data — it only orchestrates the tools/ extractors against your copy. Useful flags:

./install-assets.sh --dry-run   # show exactly what it would do, run nothing
./install-assets.sh --help      # full usage

Everything lands in the engine's data directory, ~/Library/Application Support/Vanilla-Conquer/vanillatd/ (classic MIX archives) and …/vanillatd/extracted/ (extracted art & audio) — the same data directory Vanilla-Conquer uses. When it finishes, just swift run.

Manual extraction (fallback)

If you prefer to run the steps yourself, there are two asset sources:

1. Classic game data (MIX archives) — the original sprites, maps, audio, and scenarios. The engine reads these from ~/Library/Application Support/Vanilla-Conquer/vanillatd/. (The classic .MIX files from the Remastered Collection's CNCDATA/TIBERIAN_DAWN/CD1 (GDI/shared) and CD2 (Nod) go here — the shared archives in the root, the side-specific GENERAL.MIX/SCORES.MIX/MOVIES.MIX in gdi/ and nod/.)

2. Remastered HD art & audio (optional but recommended) — extracted from the Remastered Collection's .MEG archives into …/vanillatd/extracted/. With the Remastered install downloaded to ~/CnCRemastered/Data:

   pip install Pillow
   python3 tools/extract_remastered_sprites.py            # HD units/structures/vfx
   python3 tools/extract_remastered_sprites.py --category ui   # HD cursors + sidebar meters
   python3 tools/extract_remastered_audio.py              # HD music & sound
   python3 tools/extract_audio.py                         # classic AUD → WAV (from MIX)

Build & run

brew install sdl2 pkg-config
swift build          # or: swift run
./TiberianDawnMax.command   # convenience wrapper (runs `swift run`)

Headless test harness

The simulation runs without a window/renderer/audio, which powers a deterministic regression suite (see CONTRIBUTING.md):

./.build/debug/TiberianDawnMax --determinism SCG01EA 2500   # 3 subprocess trials, assert identical
./.build/debug/TiberianDawnMax --headless    SCG01EA 600    # run + print a state digest
./.build/debug/TiberianDawnMax --test-crush   SCG01EA        # focused behavior self-tests

The seeded RNG makes runs bit-for-bit reproducible, so a change that perturbs the simulation shows up as a changed digest. Please keep the determinism baselines green when changing simulation code.

Contributing

Contributions are very welcome — see CONTRIBUTING.md. A lot of the roadmap is data work (rules, missions, unit tables) that doesn't require deep Swift knowledge. Never commit game assets.

docs/PARITY.md is the honest map of how close the simulation is to the original — what's verified, what's approximated, and what's missing. Several rows there are self-contained starting points.

License

GNU General Public License v3.0 — see LICENSE.

OpenConquer builds on the behavior of the Tiberian Dawn game logic that Electronic Arts released under the GPLv3 in 2020, and cross-references Vanilla-Conquer (also GPLv3). Licensing OpenConquer under GPLv3 keeps it compatible with that lineage.

Copyright © 2024–2026 David Clawson and contributors.

Credits & thanks

• Electronic Arts / Westwood Studios — the original game, and the 2020 GPLv3 source release that makes faithful reimplementation possible.
• Vanilla-Conquer and the OpenRA project — invaluable references and inspiration for the open-source C&C ecosystem.