# Portal 2, statically recompiled for Apple silicon

[![Portal 2 running natively on iPhone (video)](https://img.youtube.com/vi/YWX2BeMnlQI/maxresdefault.jpg)](https://youtu.be/YWX2BeMnlQI)

*Video: Portal 2 running natively on an iPhone 15 Pro Max.*

<p>
  <img src="docs/images/iphone-menu.jpg" alt="Portal 2 main menu on iPhone, 60 fps" width="49%">
  <img src="docs/images/iphone-ingame.jpg" alt="Portal 2 in game on iPhone with touch controls" width="49%">
</p>

This project turns the Linux version of Portal 2 into a native ARM64 app for
macOS and iPhone. The game's x86 machine code is translated into C and
compiled: no emulator, no Wine, no Rosetta. A small runtime provides what the
Linux binaries expect (libc, threads, SDL2, graphics, Steam).

- **Mac**: fully playable, 235–280 fps on an M3 Pro (1280×720 to 1512×982).
- **iPhone**: fully playable on an iPhone 15 Pro Max at a steady 60 fps, with
  touch controls and portals fired by **tapping the back of the phone**.

**You must own Portal 2.** This repository has no game files and no Valve
code: everything is generated on your machine from your own copy. The app and
the generated code contain Valve's game, so keep them for yourself and don't
share them.

> Unofficial fan project, not affiliated with or endorsed by Valve. Portal,
> Portal 2, Steam and Source are trademarks of Valve Corporation. Provided as
> is, without warranty.

## What you need

- An Apple silicon Mac with Python 3, [Homebrew](https://brew.sh) and the
  Xcode command line tools (`xcode-select --install`), then
  `brew install sdl2 freetype fontconfig`.
- Portal 2 on Steam:
  - the game folder (the one with `portal2/`, `platform/` and `bin/`); the
    Windows version works;
  - the Linux binaries: open the Steam console (`open steam://open/console`)
    and type `download_depot 620 661` (about 90 MB).
- Optional but recommended: [Rust](https://rustup.rs), for the faster Metal
  renderer.
- For iPhone: Xcode with your Apple ID (a free account works),
  `brew install xcodegen cmake ninja`, the iPhone connected by cable with
  Developer Mode on, and about 12 GB free on it. Tested on an iPhone 15 Pro
  Max only.

## Install

```sh
git clone https://github.com/kanapitsas/portal2-recomp.git
cd portal2-recomp
./setup.sh "/path/to/Portal 2" "/path/to/depot_661"          # Mac
./setup.sh --ios "/path/to/Portal 2" "/path/to/depot_661"    # Mac and iPhone
```

Without paths, `setup.sh` looks where Steam usually puts them. It builds the
game (about 10 minutes the first time) and creates
`~/Applications/Portal 2 Natif.app`. Re-running it is safe and quick.

The app contains its own executable and libraries; the game files stay where
Steam put them. After a rebuild or a change to `config/local.json`, run
`python3 tools/make_app.py` to update the app.

**iPhone**: first create an Apple Development certificate (Xcode > Settings >
Accounts > Manage Certificates > + > Apple Development). `setup.sh --ios`
then builds, signs and installs the app and copies the game data (about
11.5 GB, once; `tools/ios_device.sh data` copies it again after a reinstall).
On the phone, trust your account in Settings > General > VPN & Device
Management. With a free account, re-run `./setup.sh --ios` every 7 days.
More in [docs/ios.md](docs/ios.md).

## Play

On Mac, open Steam with the account that owns Portal 2, then open
**Portal 2 Natif** (it starts Steam if needed).

On iPhone: left stick to move, right half of the screen to look, buttons to
jump, crouch, use and pause, and a tap on the back of the phone (left or
right) to fire a portal. Everything is tunable in Settings > Portal 2. The
iPhone version is single player and offline.

## Renderer: Metal or OpenGL

The game renders with **Metal** when `libd3d9metal` is available, and with
**OpenGL** otherwise. Metal measured about +50 % fps on a Mac and +20–25 % on
an iPhone, and fixes the too-dark image of OpenGL on iPhone.

- If Rust is installed, `setup.sh` fetches and builds `libd3d9metal` (about a
  minute) from a pinned commit of
  [mtld3d's native host branch](https://github.com/kanapitsas/mtld3d/tree/feat/native-host).
  Without Rust, or if that build fails, it says so and the game uses OpenGL.
  `P2_NO_METAL=1 ./setup.sh` skips it.
- The end of `setup.sh` tells which renderer the Mac app uses. The iPhone
  library is built separately and can still fall back to OpenGL.
- `P2_RENDERER=opengl` forces OpenGL; on iPhone, use Settings > Portal 2 >
  Rendu.
- **F3** on Mac shows the renderer and the frame rate; on iPhone, the counter
  in the top-left corner does.

Details: [docs/d3d9-bridge.md](docs/d3d9-bridge.md).

## Uninstall

```sh
./uninstall.sh
```

It asks before moving the app and its log to the Trash, and asks again for
the saves. It never touches the Steam game files or the Linux binaries.

## More

- [Language and manual build](docs/usage.md)
- [iOS port, controls and settings](docs/ios.md)
- [Metal renderer](docs/d3d9-bridge.md)
- [Steam bridge](docs/steam.md), [fast memory mode](docs/fast-path.md),
  [OpenGL audit](docs/gl-audit.md), [lifter coverage](docs/lifter-coverage.md)
- [STATUS.md](STATUS.md): the development log, with every measurement

**Tests**: GitHub Actions runs the Python tests and the runtime checks (also
under UBSan). It cannot build the full game, whose files are not in the
repository.

**Limits**: built and tested against one release of the Linux binaries
(depot 661, manifest 8940703274703023246); another release needs new
indirect call roots. iOS has no co-op, achievements or Steam features. A free
Apple account allows 3 sideloaded apps and 7-day profiles.

## Credits

- [mtld3d](https://github.com/athei/mtld3d) (zlib) by Alexander Theissen,
  the Direct3D 9 on Metal behind the Metal renderer; its Wine-free build is
  discussed in [athei/mtld3d#1193](https://github.com/athei/mtld3d/issues/1193).
- [gl4es](https://github.com/ptitSeb/gl4es) (MIT) by ptitSeb, patched for iOS.
- [SDL2](https://libsdl.org) (zlib), [FreeType](https://freetype.org) (FTL).
- [Steamworks.NET](https://github.com/rlabrecque/Steamworks.NET) (MIT), whose
  interface metadata generates the Steam bridge.
- Touch controls inspired by
  [MacNativeGames](https://github.com/ly05010419/MacNativeGames) (MIT).

Built in October 2026 by Raphaël Kanapitsas, with AI coding agents
(Anthropic's Claude Code and OpenAI's Codex) writing most of the code under
his direction. The history and [STATUS.md](STATUS.md) show the whole process.

## License

[GNU GPL v3.0](LICENSE). It does not cover Portal 2 or any Valve material.