OpenGTPS1

OpenGTPS1

OpenGTPS1 0.9b is an experimental static-recompilation port of the US Gran Turismo 2 Simulation Disc (SCUS-94488, NTSC-U revision 2) and Arcade Disc (SCUS-94455, NTSC-U), built with RecompOne.

The project currently targets Windows x64. It boots through the original game flow, renders menus and videos, supports controllers and memory cards, and can run a purchased and upgraded car through complete races, championships, and replays. Its portable native race/replay renderer is designed to support both modern PCs and, in a future port, the original Xbox through NXDK.

[!IMPORTANT] 0.9b needs broad community testing. Please play both modes, try your controllers and existing saves, and report crashes, visual defects, audio problems, and performance regressions through the public issue tracker. Use New issue to include your hardware, reproduction steps, and logs\OpenGTPS1-latest.log.

[!IMPORTANT] This repository contains no Gran Turismo 2 disc data, Sony BIOS, music, save files, or other copyrighted game assets. You must supply your own matching disc. Do not open an issue asking for game files.

The unified main menu launches Arcade Mode, Gran Turismo Mode, Replay Theater, and options from one executable.

Project status

OpenGTPS1 0.9b is playable on Windows x64, but it is not a finished 1.0 release. Active development is entering a hiatus; testing and detailed issue reports are especially valuable while work is paused.

• The unified Windows port boots the original GT2 opening and offers native Arcade Mode and Gran Turismo Mode from one title menu.
• Complete races, championships, results, and native replays are playable.
• Menus, videos, input, memory-card persistence, sound effects, and XA audio are implemented.
• Valid Simulation saves are loaded before the unified title, and their full native payload—including credits, licenses, garage, current car, and records—follows the handoff into Arcade Mode's Home Garage.
• The distributable runtime uses loose files only; it never needs a mounted or adjacent BIN/CUE/CCD/IMG/SUB image after preparation.
• External OGG music, fixed modern graphics settings, structured logging, and a deterministic AI-driven test harness are available.
• The packaged native race/replay renderer uses perspective-correct resident course geometry, exact road-seam handling, extended draw distance, maximum vehicle LOD, and geometry-aware 59.94/60 Hz presentation. Provenance-backed 3D never reaches a PS1-era compatibility rasterizer. GT2's authored screen-command compositor remains in use for menus, videos, HUD layers, Results, and world-free transitions; it is the 2D layer of the modern presentation path, not a selectable legacy 3D renderer.
• True horizontal-plus widescreen and the fixed authored-world renderer are implemented, but visual defects and hardware-specific problems may remain.
• Original Xbox support has not landed yet.

Screenshots

Red Rock Valley starting grid	Seattle Circuit
Midfield Raceway	Trial Mountain

Open issues and testing priorities

The current known defects are tracked in TO-DO.MD:

• The generated prize/LM development smoke-test save gives some cars incorrect wheel widths.
• At least the black JGTC Castrol Supra can revert to white when a race begins.
• The planned original-Xbox port has not been implemented.

The 0.9b Windows release needs user testing across more hardware and ordinary play patterns. The highest-value reports cover:

• fresh setup with the exact supported two-disc set;
• Xbox-compatible controllers and keyboard input from the first title-menu press through full races;
• creating, loading, updating, and backing up memory cards, including Arcade Home Garage use;
• full races and replays on every course, with attention to starting grids, vehicle reflections, flicker, seams, pop-in, and paint/livery persistence;
• sustained performance, especially cases that fall materially below the intended roughly 55–60 FPS range;
• XA music, sound effects, external OGG playback, and device-specific audio behavior.

Please search the open issues before filing, then use New issue and attach the latest bounded log whenever possible.

TO-DO.MD is the detailed implementation and validation record. docs/PORT_PLAN.md documents the playable vertical slice and the RecompOne-specific discoveries behind it. The modern renderer architecture defines the shared PC and original-Xbox direction.

Unified installation and GT1 conversion status

The 0.9b release includes a self-contained graphical first-run installer. Launching GranTurismo2PC.exe without prepared data opens it automatically. It searches nearby folders and removable drives for the exact supported disc images, provides ordinary Browse buttons when they are elsewhere, validates the complete images, and builds the unified installation locally. No command line, PowerShell window, Python installation, or PlayStation BIOS is needed.

Gran Turismo 1 merging is an optional installer feature. Select your own supported US Gran Turismo image (SCUS-94194) to add Special Stage Route 11, the completed native GT1 car imports, GT1-only paints and liveries, and the converted Racing Modification body/paint families to both applicable GT2 modes. Conversion happens locally from the user's image; the source image is never copied, modified, or retained, and the release contains no GT1 data.

The development conversion pipeline now validates the US Gran Turismo image and imports Special Stage Route 11, all three GT1-exclusive EUNOS ROADSTER Arcade families, and the GT1 Civic Racer as native GT2 data. It converts all six Route 11 variants and the authored dawn3 background, preserves the exact ARCADE.DAT entry 81 selection art, and adds the Roadsters as the tenth through twelfth Class C entries with their original wordmarks and all twenty-three authored GT1 paint/livery palettes. The third entry is the six-palette 145 PS EUNOS ROADSTER RS, whose separate GT1 day/night models are structurally converted to native GT2 CDO/CNO data without substituting GT2 body geometry. The Civic Racer is a native tenth Class B entry with its unique body and all three turquoise, pink, and yellow GT1 liveries. The GT1 DB7 Coupe is a native ninth Class A entry with its exact selection artwork and all three white, burgundy, and deep-purple paints. The GT1 Impreza WRX-STi Version III is a native tenth Class A entry with its unique converted body and all three liveries. The GT1 Soarer 2.5GT-T VVT-i is the eleventh Class A entry with its exact selection artwork, unique converted day/night body, and all three wine-red, yellow, and purple palettes. The GT1 Supra RZ is the twelfth Class A entry with its exact selection artwork and three turquoise, purple, and bronze GT1 liveries. The GT1 S13 Silvia Q's 1800cc is a native thirteenth Class C entry with its original named menu artwork and three wine-red, yellow, and green palettes. The GT1 Lancer Evolution IV GSR is the thirteenth Class A entry with its exact named logo and yellow, teal, and purple palettes. The GT1 Alcyone SVX S4 is the eleventh Class B entry with its exact named logo and white, blue, and purple palettes. The GT1 Celica SS-II is the twelfth Class B entry with its exact named menu art, structurally converted body/UV data, teal, purple, and yellow palettes, and target-owned 1,220 kg chassis record. The GT1 Civic CR-X '91 Si is the thirteenth Class B entry with its exact named Honda/CR-X art, structurally converted UV-preserving body, black, yellow, and purple palettes, and target-owned 970 kg chassis record. The deterministic GTPATCH.VOL also carries sorted native Racing and Drift parameter records assembled from the matching GT2 V-Special chassis/suspension, S-Special wheel/tire package, GT1-equivalent Mazda brake conversion, and direct Roadster RS, Civic, DB7, Impreza, Soarer, Supra, Silvia, Lancer, Alcyone, Celica, and CR-X specifications. Menu-to-race smokes have run the track and all thirteen cars under GT2's native AI controller without an unmapped call, managed exception, or software fault. Remaining exclusive cars and livery families are the next content milestone.

Install the 0.9b Windows release

The prebuilt release requires:

• Windows 10 or 11, x64
• Your own supported US Gran Turismo 2 Simulation Disc, revision 2
• Your own supported US Gran Turismo 2 Arcade Disc
• Optionally, your own US Gran Turismo disc to merge supported GT1 content

Other regions and revisions are not supported. The required raw Mode 2/2352 images are:

Serial:  SCUS-94488
Size:    691,850,208 bytes
SHA-256: D0AB6E70539601057590A36299543C0ADAD219254D712F7D4273219094ED5031

Serial:  SCUS-94455
Size:    729,423,408 bytes
SHA-256: C2E97D6B0C847CA4336D9D84D8D98C349D1240ED075E81AB3FD5C977E9A45075

Optional Gran Turismo content source
Serial:  SCUS-94194
Size:    693,668,304 bytes
SHA-256: 765A748C4F2975A063A47BA9E42708A4882954D765F9E352C5AF3C0950EAEFB6

The release contains no game data. To install:

1. Download OpenGTPS1-0.9b-win-x64.zip from the GitHub release.
2. Extract the entire OpenGTPS1-0.9b-win-x64 folder to a writable location. Do not run it from inside the ZIP.
3. Rip both matching GT2 discs as raw Mode 2/2352 .img files. Rip the optional matching GT1 disc too if you want its converted content merged.
4. Run GranTurismo2PC.exe. The first-run setup window searches for the images and lets you Browse to any it does not find.
5. Choose whether to merge GT1 content, select Install and play, and wait for the completion message. Later launches go straight to the game.

Setup validates both complete disc hashes before writing anything, extracts only the required runtime files beside the executable, and does not copy or retain any source IMG. When selected, GT1 conversion and merging are performed by the same setup window. The game creates blank carda.sav and cardb.sav memory cards on first launch. The package is self-contained; users do not need Python, the .NET runtime/SDK, CMake, Visual Studio, or a PlayStation BIOS.

Keep the installation in a writable folder because saves, settings, and the latest diagnostic log are stored beside the executable. Windows SmartScreen may warn because this beta is not code-signed.

The ZIP also contains an installation-focused README.md. Existing users should back up carda.sav, cardb.sav, and settings.json before replacing an older build.

Build requirements

Building from source additionally requires:

• Python 3
• .NET 10 SDK
• CMake and a Visual Studio C++ x64 toolchain

The archival inputs must use these exact names in the repository root:

Gran Turismo 2 [Simulation Disc] [U] [SCUS-94488].cue
Gran Turismo 2 [Simulation Disc] [U] [SCUS-94488].img
SCUS_944.55.cue
SCUS_944.55.img

Other dump formats and game revisions are not currently supported. Disc files and all extracted/generated data are excluded by .gitignore.

Build from source

Clone the repository, place both matching CUE/IMG pairs in its root, and run:

python tools\extract_disc.py
powershell -ExecutionPolicy Bypass -File tools\build.ps1 -Regenerate

Recompilation creates ignored developer output under generated\. Packaging creates the one-folder installation under OpenGTPS1\:

OpenGTPS1\
  GranTurismo2PC.exe
  interface.ini
  GT2.VOL
  manifests\
    arcade.json
    simulation.json
  arcade\
  simulation\
  music\

After the first regeneration, ordinary rebuilds do not read the archival disc image:

powershell -ExecutionPolicy Bypass -File tools\build.ps1

Run the packaged executable directly:

OpenGTPS1\GranTurismo2PC.exe

Or launch the development build:

powershell -ExecutionPolicy Bypass -File tools\run.ps1

Controls

Xbox-compatible controllers map to the equivalent PlayStation controls. Default keyboard bindings are:

PlayStation control	Keyboard
D-pad	Arrow keys
Cross / accelerate	Z
Circle	X
Square / brake	A
Triangle	S
Start	Enter
Select	Right Shift
L1 / R1	Q / W
L2 / R2	E / R

Bindings, display, audio, and graphics options are available in the wrapper menus.

Graphics

OpenGTPS1 has one modern 3D path. It always uses 4x source rendering, perspective-correct resident-course texture mapping, stabilized authored topology, complete authored draw distance, maximum track/scenery and vehicle LOD, smoothed sampling, and no PS1 color dithering. Old PS1 Quality, Custom, stock-distance/LOD, and native-renderer-disable configuration values are migrated to that fixed contract and cannot reactivate a compatibility world renderer.

Output resolution, fullscreen/window state, and presentation antialiasing are wrapper settings; they do not reduce world geometry or reinstate PS1 rendering.

External music

Place OGG Vorbis files next to the executable:

OpenGTPS1\music\[artist] - [song].ogg

Files are sorted into a looping queue. Artist and title labels are derived from the filename. Sound effects and video XA audio remain independent.

Diagnostics and safe automation

Each launch replaces:

OpenGTPS1\logs\OpenGTPS1-latest.log

The log is capped at 4 MiB. Attach it when reporting graphics, frame-pacing, audio, CD, or save problems.

Unattended runs must use:

OpenGTPS1\GranTurismo2PC.exe --headless

Headless mode hides the window, forces SDL's dummy audio backend, and fails closed if a physical audio device is active. For a visible but silent diagnostic session, use --mute; it does not overwrite the saved audio settings.

The scripts in tools\ include bounded capture and regression helpers. The input fixtures under tests\fixtures\ drive deterministic game flows; they do not contain game data.

The modern-renderer branch includes bounded projected- and world-scene bridges. tools\capture_projected_scene.ps1 captures one live draw stream plus VRAM and renders independent perspective and affine PNGs through the portable C++ core. tools\capture_world_scene.ps1 additionally captures upstream model/view coordinates, camera transforms, stable track/vehicle identity, exact per-vertex projection state, materials, and original draw order, then validates and exports the scene through the native loader.

The branch now also builds opengt_world_viewer.exe, a standalone D3D11 backend over the API-neutral C++17 world draw list. It supports hardware rendering, deterministic WARP validation, perspective-correct PS1 materials, object-scoped depth that preserves GT2 ordering layers, explicit optional dithering, CPU-oracle comparison, a --window inspection mode, and viewer-only --scale 1 through --scale 8 diagnostic output. The scale switch rerasterizes at the requested size and is separate from the deferred wrapper resolution/widescreen work.

World-capture format version 4 supplies capture-stable authored track vertex identity. The portable topology pass uses that identity plus exact integer GTE view coordinates to join authored sector boundaries, subdivide exact T-junctions, and choose deterministic ownership for same-material coplanar overlap. It performs no proximity search or screen-space triangle expansion. The D3D11 point sampler also treats PS1 integer UVs as texel centers; this removes the intermittent Red Rock replay road line around 0:33 without padding. The same native renderer is integrated into packaged live race/replay presentation; the standalone viewer remains available for deterministic capture inspection and renderer development.

Validate a captured world frame twice with bounded lossless PNG output:

cmake -S native -B build\native
cmake --build build\native --config Release
powershell -ExecutionPolicy Bypass -File tools\validate_world_renderer.ps1 `
  -Capture artifacts\modern-world-v4-topology-live\race-frame.ogtwcap

See docs/MODERN_RENDERER.md for the formats, exact commands, audio-safety checks, and next renderer milestone.

Repository layout

docs\                  Port notes and architecture documentation
tests\fixtures\        Deterministic input/configuration fixtures
tools\                 Extraction, build, packaging, capture, and test tools
vendor\RecompOne\      RecompOne source plus OpenGTPS1 runtime changes
generated\             Ignored generated recompilation output
OpenGTPS1\             Ignored one-folder local deployment
work\                  Ignored extracted and intermediate game data
artifacts\             Ignored local captures, saves, and test evidence

Legal

Gran Turismo and Gran Turismo 2 are trademarks of Sony Interactive Entertainment. OpenGTPS1 is an independent preservation and compatibility project and is not affiliated with or endorsed by Sony Interactive Entertainment or Polyphony Digital.

No license has yet been granted for original OpenGTPS1 code. The vendored RecompOne project retains its own license and attribution files.