Phaethon

The Precursor Legacy

Jak and Daxter

One seamless world with no loading screens, and Precursor orbs in every corner of it.

Get Phaethon The four cores
Where it stands

Runs start to finish with the fork's retail-behavior fixes.

counted in the tree at develop 32de6fb on Oct 17, 2026 · a line is one of GOAL code, not a blank or a comment · a definition is one of the game's functions, methods, states or types

292,143lines of GOAL
8,022definitions
470models with their animations
675particle effects

Status

Playable

Released

2001

Discs

SCUS-97124 (NTSC-U) · SCES-50361 (PAL)

Source files

535 in the tree at develop 6332c399

The game

A friend to turn back, across one unbroken world.

Jak and his friend Daxter sneak onto an island they were warned away from, and Daxter falls into a pool of dark eco that turns him into an ottsel, half otter and half weasel. The hunt for a way to turn him back takes them across jungles, beaches, caves and a volcano, gathering the power cells that wake the Precursors' old machines, and into the plot of a rogue sage and his sister to flood the world with dark eco.

Naughty Dog built it as one continuous world. Each area streams in while Jak walks toward it, with no loading screen between them, which critics called a new standard for the genre. Underneath is GOAL, a programming language the studio wrote for itself.

Developer
Naughty Dog
Publisher
Sony Computer Entertainment
Released
December 2001
Genre
3D platformer
Jak and Daxter: The Precursor Legacy's title screen, the game's logo and its Press Start prompt over a thatched hut on its rock island, with the sea and the cliffs beyond
How it came back

Taken back from the disc by OpenGOAL, then carried here.

Naughty Dog wrote the game in GOAL, a language of its own descended from Lisp, which compiled straight to the PlayStation 2's machine code; its source was never released. There was no C to recover. Bringing the game back meant translating every function on the disc back into readable GOAL, writing a new compiler for that GOAL, and building a runtime to stand in for the console. OpenGOAL, a volunteer project begun in 2020, did all three, and released Jak and Daxter on PC in April 2022: a native port rather than an emulator, run from the player's own disc.

Phaethon started from that work in July 2026 with the game fully decompiled: every one of its 535 files holds code, and no named function is missing its body. The work since has been making it behave as the disc does. Its logic now ticks at the console's 60 a second whatever the frame rate, the ocean's reflections come from the console's own program rather than a hand port, objects fade in at the distances the disc gives them, and its subtitles moved onto the overlay all four games share.

  1. 01

    The disc

    The player's own copy. Its archives hold the game's compiled code and all of its art.

  2. 02

    Decompiler

    Reads that compiled code back into GOAL a person can read, type-check and change.

  3. 03

    Compiler

    A new GOAL compiler builds the source for a PC's processor instead of the console's.

  4. 04

    Runtime

    A kernel, a sound and file driver and a renderer stand in for the console's hardware.

  1. PS2Jak and Daxter: The Precursor Legacy ships, written in GOAL.
  2. OpenGOALThe OpenGOAL project opens its repository.
  3. OpenGOALOpenGOAL's first release puts Jak and Daxter on PC.
  4. PhaethonPhaethon starts from OpenGOAL's tree, the game fully decompiled.
  5. PhaethonThe logic ticks at 60 a second at any frame rate, and 37 hand-written frame-rate patches are retired.
  6. PhaethonThe subtitles move onto the overlay all four games share.
  7. PhaethonLevel of detail follows the disc, so objects fade in instead of popping in.
  8. PhaethonThe ocean's reflections match the console's, its program generated rather than ported by hand.
Phaethon

Built with AI in the loop. Phaethon uses AI assistance for speed and accuracy, and holds it to the same bar as every other contribution: every change is read, tested and checked against the console before it lands.

Project

About FAQ Docs

Cores

Jak and Daxter Jak II Jak 3 Jak X: Combat Racing

Play

Download the launcher Import a disc System requirements Your account

Community

Report a bug Contact
develop 6332c399 CI green v0.2.1 Nov 4, 2026

Phaethon is an unofficial fan project. It is not affiliated with, endorsed by or associated with Sony Interactive Entertainment, Naughty Dog or the OpenGOAL project. Jak and Daxter is a trademark of Sony Interactive Entertainment. You need your own copy of each game. Icons from Lucide, ISC; JetBrains Mono under the SIL Open Font License.

Under construction

This site is still being built.

Nothing links to playphaethon.com yet, so you have found it before it is ready. Some of what it says may be wrong, out of date or attributed to the wrong source. Treat it as a work in progress until this notice is gone.