OpenHP1 (Harry Potter)

Experience the first Harry Potter PC game as if you were sitting in front of your old Windows 98/XP PC, but on current hardware and operating systems, and without the glitches and difficulties that come with installing and running an old game.

OpenHP1 requires the original game files to run.

Supported Platforms

Platform	OS Version	Architecture	Renderer
Windows	10 or higher	x86_64, ARM64	DirectX 12
macOS	11.0 or higher	Intel, Apple Silicon	Metal
Linux1	5.4 or higher	x86_64, aarch64	Vulkan

Features

The game is playable from start to finish. I have completed a full playthrough without encountering any major or game-breaking issues. Minor graphical and behavioral differences from the original game may still exist, and some animations or interactions might not behave exactly as intended, but none of these are currently known to prevent progression or significantly affect gameplay.

Goodies

While our primary goal is to keep as true as possible to the original game experience, there are lots of nice optional tweaks and additions that make the game nicer to play on modern hardware. The graphics settings in particular have been replaced by a fully custom menu with a lot more options.

Resolutions

OpenHP1 supports a wide range of resolutions, from the original low-res 4:3 to modern high-fidelity widescreen formats. The internal resolution is fully independent of window size.

Kind	Description
Classic	Legacy resolutions of the original game, keeping a true 4:3 aspect ratio.
Enhanced	Same as Classic, but at higher resolutions that didn't exist in the original game.
Widescreen	Fills the window, showing more of the level on the sides instead of forcing 4:3.

Renderers

OpenHP1 ships with multiple configurable renderers, so you can get exactly the look you want.

Name	Description
Classic	True to the original game, with optional 16-bit emulation.
Modern	HDR, Tone Mapping, Brightness/Contrast, Ambient Occlusion and more.

What is 16-bit emulation?
While the game defaults to 32-bit, allowing it to display a wide range of colors, we also ship an emulated 16-bit mode (RGB565). This essentially compresses the available color spectrum to approximate the look of the game on old 16-bit hardware.

Which renderer should I use?
If you like the look of the original game, just keep the default. The classic renderer very closely approximates the look of the original game running on old hardware. It's fast, simple, and renders the game in the way it was supposed to be rendered.

The modern renderer is exactly what it says on the package. A much more modern renderer with fancy post-processing, anti-aliasing, ambient occlusion, bloom and more. It's certainly not what the game looked like back then, but everything is carefully fine-tuned to not change the look and feel too much while still delivering an elevated experience worthy of modern hardware.

Installation

OpenHP1 requires original game data but does not distribute it. Start openhp1-launcher, choose the original game folder containing Maps and System, select one of its available languages, then select Play. The launcher remembers the validated folder and language in OpenHP1.ini.

For building the game yourself, please refer to the Development section below.

Development

Prerequisites

Place the original game files in the res/ directory. It should look something like this:

res/
├── Maps/
│   ├── Lev_Tut1.unr
│   ├── Lev_Tut2.unr
│   └── ...
├── Music/
├── Sounds/
├── ...

You will also need a modern Rust toolchain installed. You can install Rust with rustup.

Map Viewer

The OpenHP1 viewer is a cross-platform, real-time 3D renderer for the original Harry Potter 1 maps and actors. It does not implement the full game logic, but it lets you fly through the original levels and inspect the actors, meshes, and textures. Click a visible surface to inspect its qualified texture name and material flags in the sidebar.

You can build and run the viewer with:

cargo run -p openhp1-viewer -- res/Maps/Lev_Tut1.unr # debug build
cargo run -p openhp1-viewer --release -- res/Maps/Lev_Tut1.unr # release build

Window Mask Editor

The window editor reads candidate window textures directly from the configured original game installation. Click colors to add include or exclude rules, adjust their similarity thresholds and optional pixel radius, drag rectangular hard exclusions, and inspect the source, mask, or overlay preview. Rules are saved to the committable window_editor.state.json; exported 8-bit grayscale PNGs under window_masks/ contain only the authored mask, not original texture pixels. Black blocks light and white transmits it. The Modern renderer embeds matching exported masks and continues using its luminance fallback for configured windows that do not have one yet.

cargo run -p openhp1-window-editor

Game

The OpenHP1 game is a re-implementation of the original game logic. It intends to faithfully reproduce the original gameplay.

You can build and run the game with:

cargo run -p openhp1-launcher # launcher and game-data configuration
cargo run -p openhp1-game # debug build
cargo run -p openhp1-game --release # release build

Press the ` key to open the bottom developer console, enter commands, and press it again to return to the game. The console keeps command/output history for the current session; use up/down to revisit commands and help to list registered commands.

To build the release versions for all platforms, install cross, cargo-xwin, and LLVM, start Docker or Podman, then run:

./scripts/release.sh

Docs

See docs/ for the reverse-engineered package, map, texture, and rendering notes.

Resources

Original game data may remain in an external folder selected through the launcher. For development, the gitignored res/ directory is also detected automatically. Original game data must never be committed or distributed with OpenHP1.

Footnotes

1. Linux kernel 5.4 or later and glibc 2.31 or later are recommended, along with a Vulkan-capable GPU with suitable drivers. Older systems may work as well; the provided binaries currently require glibc 2.18 or later. ↩