What you need

You need your own disc or disc image of each Jak game you want to play. The port reads its files from a disc dump; it does not ship or download any of them for you.

Before it starts extracting, the launcher reads the disc image's PlayStation 2 system file and checks the serial against what it knows, so a Jak II disc on the Jak 3 tile gets caught before it wastes your time on a bad extraction:

Game	Known disc serials
Jak and Daxter	SCUS-97124 (NTSC-U, Black Label and the later print), SCES-50361 (PAL), SCPS-15021 (NTSC-J), SCPS-56003 (NTSC-U)
Jak II	SCUS-97265 (NTSC-U), SCES-51608 (PAL), SCPS-15057 (NTSC-J), SCKA-20010 (NTSC-K)
Jak 3	SCUS-97330 and SCUS-97516 (NTSC-U, including the Greatest Hits print), SCES-52460 (PAL), SCKA-20040 (NTSC-K)
Jak X: Combat Racing	SCUS-97429, SCES-53286

A serial that is not on this list is not refused outright: the launcher hands it to the extractor's own database rather than guessing at it.

The launcher itself is a Windows desktop application, so the launcher road needs Windows. The port renders through Vulkan by default, with the OpenGL backend kept. The remastered preset's upscalers need matching hardware: DLSS needs an NVIDIA GPU, and FSR runs through AMD's FSR 3.1.

Installing and importing your disc

1. Install the launcher with its install wizard, PhaethonLauncher-Setup.exe, from the launcher page. It installs the launcher for your Windows account alone, without administrator rights.
2. The first run opens a short setup: where the runtime and every game's data should live (one folder for all four games, %UserProfile%\Phaethon by default, a folder your Windows account can write without administrator rights, each game's data kept apart underneath it), four preferences (Discord presence, staying signed in, the runtime's update check at start, and Send crash and usage reports), and an optional sign-in to a Phaethon account. You can install the runtime right from the setup or finish it and explore first; The launcher covers each page and what it changes. How thoroughly update checks verify what is already on disk is set in Settings instead.
3. Open a game's page and point its disc field at your disc image. Starting the import runs the fork's extractor through three stages you can watch progress on: extract, decompile, compile.
4. Once it succeeds, the launcher records when the import happened, and the game's card in your library reads ready to play.

Everything the import produces lands under the install folder's data subdirectory: the extracted disc under iso_data\<game>, the compiled build under out\<game>\iso. The launcher's own settings, its per-game records (disc path, preset, extra launch arguments, enabled modes) and its crash logs live separately, under %AppData%\PhaethonLauncher.

First launch

Play starts gk.exe from the runtime folder with the runtime's own options first, then --, then the arguments the game reads. For Jak X, retail-faithful, in the default install folder of a Windows account whose user folder is C:\Users\you, the line is:

gk.exe --game jakx --proj-path C:\Users\you\Phaethon\data -- -boot -fakeiso

With the game's Remastered checkbox on, it is:

gk.exe --game jakx --proj-path C:\Users\you\Phaethon\data --preset remastered -- -boot -fakeiso

With the checkbox off, the launcher passes no --preset at all, and the runtime boots retail. After -boot -fakeiso come -debug when the game's Debug mode is on and the launcher's debug tooling is enabled, -movies with the upscaled cutscenes' folder when that mode is on, and any extra arguments you set per game; the Game page's What Play runs card shows the exact line. Every game starts retail-faithful; the enhancements are individual toggles in the game's options and the launcher, covered on Settings and the remastered toggles.

Building from source instead

If you would rather compile the game yourself from a checkout of this repository, the toolchain, the task commands and the REPL road are on Building from source.

When something goes wrong

Start on Reporting a retail divergence if what you are seeing is the port behaving differently from the PlayStation 2 original; that form asks what retail does and how you know, which is what makes a report useful. For a crash or a hang, the game's log sits under %APPDATA%\Phaethon\<game>\log\; attach the newest one, and the crash block too if the game printed one. Anything else goes through the issue forms, which cover general bugs, performance and feature requests as well.

Phaethon is a hard fork of OpenGOAL's jak-project. Naughty Dog made the games; you need your own copy of each. built from the wiki · 12 Nov 2026