Downhill Revived

A PC port of Downhill Domination.

Downhill Revived is a native 64-bit Windows port of Downhill Domination (PlayStation 2, Incognito Entertainment / SCEA, 2003), with experimental builds for Macs with Apple silicon and for 64-bit Linux. It is built on a matching decompilation: C/C++ source that compiles back to the original game program byte for byte. The port takes that source, builds it for the PC and replaces the PS2 hardware with native code. It adds a modern renderer, PC display options, the game's movies, memory card saves, texture packs, online races, a launcher and automatic updates.

News, help and races: the Discord server.

• This is a fan project. It is not made, endorsed or supported by Sony Interactive Entertainment, Incognito Entertainment or anyone who holds rights to the game.
• This repository and its releases contain no game data: no disc image, no game executable or data from it, no IOP modules, no textures, sound, music or movies, and no BIOS. dhd.exe is the translated code only; at every start it reads the game's data (strings, tables, vector unit microcode) from your disc image, after checking it is the unchanged original.
• To play you need your own copy of the game: the USA disc (SCUS-97177), dumped by you to an .iso file. Other regions and modified images are not supported (why: docs/findings/100-other-releases.md).
• The project takes no donations and sells nothing.

What works today:

• A launcher, DownhillRevived.exe: it opens before the game and holds the settings, your rider name for online races, the disc image, updates, the release notes, the public races on the server and a link to the Discord server. It works with a controller too.
• Discord Rich Presence: your Discord profile can show the menus, the race with its track and your place, the career or the online room (never a private room's code). Off in the launcher: Online > Discord status.
• Native renderer on Direct3D 12 or Vulkan, written in Rust on wgpu. The original PS2 graphics hardware is reproduced on the GPU. An exact emulation path stays in the code as the reference it is tested against.
• 60 fps or more, with even frame pacing. The game runs at its original 59.94 Hz, and each picture is shown on a fixed grid, so frames don't come out long-short-long. PC SETTINGS > Frame Rate also offers 120, 144, 165 or 240 fps, or the monitor's rate; online races stay at 60. Pad input is read as late as possible before each frame.
• Higher resolution and widescreen. Internal resolution 1x to 8x (or matched to the window). Widescreen at the monitor's shape (16:9, 21:9 or any other) is Hor+: a wider view with the same vertical framing, and the HUD, menus and 2D screens keep their shape. Windowed, borderless and exclusive fullscreen. A new install starts borderless at 2x in widescreen, at the monitor's resolution.
• The movies play: the intro, the attract loop and OPTIONS > VIDEO CLIPS, decoded with libmpeg2 from your disc. Skip Movies in PC SETTINGS (on in a new install) skips them.
• PC SETTINGS in the game's own OPTIONS menu: resolution, display mode, window size, picture shape, scaling, widescreen, skip movies, vibration, texture pack and font, drawn with the game's own menus and font. Changes are saved to dhd.ini. V-Sync (on in a new install) shows each picture without tearing.
• Unlock All (PC SETTINGS, off by default): every track, rider, bike and shop item reads as unlocked while it is on. Your save isn't changed, so turning it off brings your own progress back.
• A sharp font: the game's text is drawn with clean edges at any resolution, made in memory from the font on your disc (PC SETTINGS > Font: Sharp or Original).
• Texture packs: replacement packs made for PCSX2 (PNG files named by PCSX2's texture hash) work unchanged with the native renderer (see Texture packs).
• Automatic updates: at start the game looks for a newer release and offers to install it; your settings and saves are never touched.
• The mouse in the menus: hovering selects, a left click is X, a right click goes back and the wheel scrolls a list or changes a value.
• EXIT GAME in the main menu.
• Online races for 2 to 4 players (experimental): an ONLINE entry in the main menu, a list of public races, private races joined with a 6-character code, and a race room where the host picks the track, on the project's official server (see Online). After the results the game goes back to offline play with your own controller (TRY AGAIN, NEW LEVEL or QUIT).
• Memory card saves, stored as plain files beside the game.
• Controllers: Xbox pads, DualSense, DualShock 4, Switch Pro, 8BitDo and most other USB or Bluetooth pads (through SDL3 and its controller database), with vibration where the pad has motors. Buttons go by position, as on a PlayStation pad. The 2-4 player modes use every connected controller.
• Keyboard play: a whole race on the keyboard, with gradual steering; letters go by their place on the keyboard, so AZERTY and QWERTZ work too (see Controls).
• Sound: the game's sound driver is replaced by a native mixer, with music, effects and reverb.

Known gaps:

• Movies are shown 4:3 in widescreen, as on the PS2.
• The 2-4 player split screens have not been checked in widescreen.
• Online races have been tested with two games and two scripted players, not yet with four people on four PCs.
• The browser version (experimental) at https://downhill-revived.pages.dev/play/ needs Chrome or Edge 137 or later and a fast PC; online races are off there. It reads your .iso in place in the browser and uploads nothing. Its source is port/web.
• The game has only been tested on a few PCs. Please report problems.

1. Download DownhillRevived-<version>-win.zip from the Releases page and unzip it into a folder you can write to (not Program Files). It holds DownhillRevived.exe (the launcher), dhd.exe (the game), dxcompiler.dll (Microsoft's shader compiler), README.txt, LICENSE.txt and THIRD-PARTY-NOTICES.txt; nothing else is needed.
2. Run DownhillRevived.exe (dhd.exe opens it too) and press PLAY.
3. The first time, choose your disc image: your .iso of the USA disc. It is checked and remembered in dhd.ini; you won't be asked again unless the file moves or changes.

Mac and Linux (experimental): download DownhillRevived-<version>-mac-experimental.zip or -linux-experimental.zip instead. On a Mac, move Downhill Revived to Applications and allow it once under System Settings > Privacy & Security (Open Anyway); on Linux, unzip it anywhere you can write to and run DownhillRevived. The README.txt in the zip has the details.

To start the game without the launcher, turn off Settings > Game > Open the launcher first in the launcher (or put launcher = off in dhd.ini); dhd.exe then starts the game straight away.

Files the game keeps beside dhd.exe:

The launcher looks for a newer release when it opens and shows Update when there is one; it downloads the release, checks its SHA-256, puts it in place and opens again (auto_update = on installs without asking). Without the launcher the game itself asks at start: Update now or Later. Without a network the game just starts. An update replaces dhd.exe, the launcher and the other files of the release (the text files, dxcompiler.dll), never dhd.ini or saves\. You can also update by hand: copy the files of a newer release over your folder (a release holds no dhd.ini and no saves, so yours are kept). Online races need the newest version; an older one is offered Update Now in the ONLINE menu.

A controller works out of the box. The buttons go by position, as on a PlayStation pad: bottom = Cross, right = Circle, left = Square, top = Triangle. A pad SDL doesn't know can be added with a line in SDL's format in gamecontrollerdb.txt beside dhd.exe.

No controller? The keyboard plays a whole race (only while the game's window is in front; it works together with a controller):

Letters are places on the keyboard as on a US one: on AZERTY or QWERTZ use the keys in the same places. The game's own controls screen (OPTIONS > CONTROLS) names the PlayStation buttons; the keys above stand for them.

Online works out of the box: choose ONLINE in the main menu to create a public or private race, or join one from the list or with its code. The game uses the project's official server, wss://dhd.skuza.app. Every player needs the same USA disc image.

Running your own server is optional. online/server/ is the server (Cloudflare Workers), and online/server/README.md explains how to deploy it. Then put its address on the server = line of dhd.ini (the game writes the file at the first start):

server = wss://YOUR-SERVER-ADDRESS

An empty server = line means the official server.

Texture replacement packs made for PCSX2 work unchanged. Packs are made by their authors and are not part of this project. Either put the pack's files in textures\SCUS-97177\replacements beside dhd.exe, or name the pack's folder on the texture_pack = line of dhd.ini (for example PCSX2's own textures\SCUS-97177\replacements folder in your Documents). PC SETTINGS > Texture Pack turns it off or on at the next start.

dhd.ini beside dhd.exe holds key = value lines; the game writes it, with comments, at the first start. The PC SETTINGS page writes most of them for you.

Each key has a DHD_* environment variable (scale is DHD_SCALE, server is DHD_NET_SERVER; see docs/BUILDING.md), which wins over the file.

• Windows 10 or 11, 64-bit.
• A graphics card with Direct3D 12 or Vulkan. Without one the game draws with Windows' software renderer (WARP), slowly.
• A reasonably modern CPU: the PS2's vector units are run on the CPU.
• Or, experimental: a Mac with Apple silicon (M1 or later) on macOS 11 or later; or 64-bit Linux with glibc 2.35 or newer (Ubuntu 22.04, Debian 12, Fedora 36, Linux Mint 21 and later), a Vulkan driver and WebKitGTK 4.1 for the launcher.

The PC port and the matching build both need the original game executable, SCUS_971.77, taken from your own disc. Nothing in this repository can be built without it.

Short version (Windows 10/11, Python 3.12+, Git, LLVM, wasi-sdk, WABT, SIMDe, Rust, Visual Studio Build Tools, CMake; details in docs/BUILDING.md):

git clone <this repository>
cd <repository folder>
python -m pip install -r requirements.txt
7z e "<your dump>.iso" SCUS_971.77 -oiso
python tools/split.py
python port/tools/build_wasm.py
python port/tools/package_release.py

build_wasm.py compiles the game into one portable core, build/wasm/dhd_core.wasm. package_release.py turns it into the 64-bit dhd.exe (wasm2c, the Windows host code and the Rust renderer), checks it and writes the release zip to build/release/: the same build as the releases. python port/web/build.py makes the browser build (experimental) into build/web/.

"Matching" means that the C/C++ in src/, compiled with the game's original compiler (SN Systems ProDG 3.01, gcc 2.95.3) and the original flags, gives exactly the bytes of the retail executable. A function counts only when a tool confirms that its bytes and the whole rebuilt executable are identical to retail; nobody's word is taken for it. Sony's SDK and the compiler's own runtime are library code and are not decompiled. python tools/report.py refreshes this table and progress/report.json (an objdiff report, in the format decomp.dev reads).

Contributions are welcome: decompiling the last functions, naming and typing what is matched, port fixes, widescreen split screens, testing on other PCs.

• Read docs/STATE.md and AGENTS.md (the project's rules) first.
• To decompile a function, follow docs/WORKER.md. A function is accepted only when tools/try_func.py prints MATCH and tools/promote.py confirms the whole image still matches.
• Port changes go in port/; src/ must keep matching.
• Never commit game data, secrets or server addresses other than the official server's.

This project builds on the work of others:

• PCSX2 (GPL-3.0-or-later): the reference for how the hardware behaves. The GS memory layouts in port/gs/memory.c follow PCSX2's GSLocalMemory/GSTables. The test and comparison tools build PCSX2 from source at test time.
• The PCSX2 widescreen patch for this game, by Aced14 (pcsx2_patches): the map of values the 16:9 mode changes.
• ps2sdk: protocol and library references (no code included). The reverb presets are read from the player's own disc (Sony's libsd module).
• OpenGOAL (ISC): the SPU2 Gaussian interpolation table in port/hle/sound_gaussian.h.
• SDL 3.4.18 (zlib): the window, sound and controllers, built from its pinned release source by port/tools/sdl3.py and linked in statically.
• wgpu (MIT/Apache-2.0) with naga and the Rust standard library: the renderer (port/render); the crates linked into dhd.exe are listed with their licences in the release's THIRD-PARTY-NOTICES.txt.
• WABT (Apache-2.0): wasm2c turns the game core into C for the 64-bit build. wasi-sdk / wasi-libc (MIT option) and SIMDe (MIT) build the core.
• DirectX Shader Compiler (NCSA/MIT): dxcompiler.dll, shipped unchanged, compiles the Direct3D 12 shaders.
• Binaryen (Apache-2.0) and wasm-bindgen (MIT/Apache-2.0): the browser build.
• libmpeg2 0.5.1 (GPL-2.0-or-later): the movie decoder, port/third_party/libmpeg2, unchanged.
• xxHash (BSD-2-Clause): the XXH64 specification, from which port/net/hash.c is written, and port/gs/xxhash.h (XXH3, unchanged) for texture pack names.
• PCSX2's texture replacement names (its GSTextureCache / GSTextureReplacements hash scheme), reimplemented in port/gs/texpack.c so PCSX2 packs load unchanged.
• splat, spimdisasm and rabbitizer (MIT): splitting and disassembling the executable.
• objdiff (MIT/Apache-2.0) and decomp.dev: progress reports.
• m2c (GPL-3.0): first drafts of functions.
• decomp.me and its compilers collection, and the SN ProDG mirror by AngheloAlf: the period compilers.
• ps2dev binutils (GPL-3.0): assembling and linking.
• ps2tek, Play!, vgmstream and other PS2 projects: documentation and ideas.
• ninja (Apache-2.0), LLVM/clang (Apache-2.0 with LLVM exception), wrangler (MIT/Apache-2.0).

The full notices of the code adapted into this repository are kept with it (port/hle/audio_licenses/, file headers).

GPL-3.0-or-later. The original game, its data, names and trademarks belong to their owners and are not covered by this licence. Code adapted from other projects keeps its own notice (see Credits).