OpenReliant

OpenReliant is an open-source, faithful engine reimplementation of StarLancer, the space combat simulator developed by Warthog and Digital Anvil and published by Microsoft in 2000.

Written in Zig and built on SDL3, OpenReliant renders with Vulkan (Metal on macOS) via SDL's GPU API. It runs natively on Linux, macOS, and Windows using assets directly from your retail copy of the game.

Website · Download · Mods

<p align="center"> <img src="docs/images/predator-wireframe.svg" width="560" alt="Wireframe of the Predator light fighter exported from its .SHP model"> </p>

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Legal & Asset Policy

OpenReliant is an independent, non-commercial open-source project. It is not affiliated with, endorsed by, or associated with Warthog Games, Digital Anvil, or Microsoft. StarLancer is a trademark of its respective owner.

This repository contains no copyrighted game assets: no textures, 3D models, sound effects, music, cinematics, mission scripts, or game binaries. OpenReliant requires assets extracted from a legally owned copy of StarLancer to run. We do not support or condone software piracy.

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Current Status

OpenReliant is in beta. The whole campaign is playable from the first mission to the end, and the games saved in the original carry on.

• Flight & Combat: All ships, with the original flight model, weapons, damage, AI and cockpit displays, and 8 camera views including 3D cockpits.
• Missions: Retail and custom mission files load, and their scripts run in full, with every command the single-player missions use.
• Controls: Mouse and keyboard, flight sticks, HOTAS and gamepads, with force feedback played as rumble, and the bindings set in the game's controls screen.
• Graphics: Per-pixel shading with gamma-corrected lighting, and real-time shadows. Rendering runs at native resolution in 32-bit colour, with bloom, anti-aliasing, smooth motion at high frame rates, and more detailed explosions, shields and planets. --original restores the original graphics and sound.
• Audio: 3D positional sound with reverb and headphone HRTF.
• Mods: Archives and folders in the game's mods folder can replace or add to any of the game's files: models, sounds, music, speech, movies and missions. PNG pictures of any size can replace textures, with material maps for physically based shading (normal maps, highlights, glow and sky reflections), and the interface's shapes and backgrounds, including widescreen ones. WebM or Matroska files can replace the movies. Mods can add ship types, guns, missiles and pilots with their own faces and voices, and models built from OBJ or glTF. Scripts in Luau can change the game's records, hook its functions and the missions' commands, run on ships, missiles and turrets, draw on the display and the menus, play their own sounds in 3D and control the music, offer a page of options, add game modes and campaigns, change the game's own campaign, its missions and the KILLBOARD, change the AI's combat maneuvers, and add shaders. A mods screen turns mods on and off, sets their load order, and shows which mods replace each other's files and which mods a mod needs. The scripting API is stable from 0.8 on (What mods can do, Modding, Scripting).
• Front End: The main menu, the settings screen with its audio, controls, video and graphics, the pilot roster, the saved games and the Reliant's and the Yamato's rooms, with a new pilot's induction, the news reports, the in-game options, the simulator pod, the locker, the CD player, the briefings, the loadout, the ITAC and the story's end.
• In Development: 1.0 is next: the beta and the mission editor polished with players' feedback, and the whole campaign played through. The mission editor, OpenReliant Editor, works in an early preview with its script view, map and debugger, and grows in releases of its own. After 1.0 come multiplayer and new kinds of ships for mods, and later a standalone engine that other space games can use. See the milestones for the roadmap.

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Documentation

• User guide: installing, configuring and playing OpenReliant.
• Developer and technical documentation: the engine, the file formats, the reverse engineering and the toolchain.

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Bugs & Feedback

Open an issue with the form that fits:

• Bug report: something doesn't work, or works differently from the original game.
• Feedback: how the game plays, and anything that feels wrong or unlike the original.
• Mod or scripting problem: a mod that doesn't load or work as it should, or a problem with the scripting API.
• Feature request: something OpenReliant doesn't do yet.

A bug report asks for openreliant.log from your game folder (The log file).

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Support

OpenReliant is free. If you'd like to sponsor the time I put into it, you can buy me a coffee. It's fully optional, only if you're willing and able to.

<a href="https://buymeacoffee.com/vdmkenny"><img src="docs/images/buy-me-a-coffee-qr.svg" width="160" alt="QR code for buymeacoffee.com/vdmkenny"></a>

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Quickstart

Download the archive for your system from the latest release and extract it, then follow the installation guide: it installs the game's files from your StarLancer discs or disc images, and starts the game.

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Building from Source

Building OpenReliant needs Zig 0.17: see Building from source. CONTRIBUTING has the workflow for working on it.

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Reverse Engineering & Analysis Tools

The repository includes tools used during reverse engineering. make help lists the workflows, and CONTRIBUTING and the toolchain describe them.

The sltool utility, included with openreliant in each release, inspects, exports and packs the game's file formats. zig build sltool builds it alone from the sources, without the game. It exits with 0 on success, 2 for an unknown command (after printing its usage) and 1 on failure (with the error on stderr), so a mod's build scripts can use it:

Command	Description	Documentation
sltool cd	Inspect CD images, ISO 9660 filesystems, DiscJuggler .cdi images and Xbox discs	disc-images, xbox
sltool hog	Extract and pack .HOG archives (BIGF container / RefPack)	hog, refpack
sltool shp	Inspect .SHP 3D models; export Wavefront OBJ or glTF; build a mod's model from OBJ or glTF	shp
sltool spr	Inspect .SPR 2D interface sprites; export PNG	spr
sltool tcache	Extract texture caches to PNG	tcache
sltool fat	Extract .fat sound banks to WAV	fat
sltool speech	Decode the radio's speech files to WAV; encode WAV to a speech file for a mod	speech
sltool fm8	Extract the radio's face films to PNG frames; encode PNG frames to a film for a mod	fm8
sltool fnt	Render .fnt bitmap fonts into glyph atlases	fnt
sltool dte	List a .DTE mission's ships, triggers and script parts; disassemble its bytecode	dte
sltool save	Show what saved games hold	save
sltool stats	Parse ship, weapon, and pilot stat tables	stats
sltool dreamcast	Read the Dreamcast version's text tables and texture cache; export its textures to PNG	dreamcast
sltool trek	Read Star Trek: Invasion's archive, missions and models; its missions share StarLancer's format	star-trek-invasion
sltool bsg	Read Battlestar Galactica's missions, its command catalogue, its comms films and its archives; convert its models to glTF and its textures to PNG; its missions keep StarLancer's records	battlestar-galactica
sltool tim	Convert PlayStation TIM pictures to PNG	playstation

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Repository Layout

Directory	Contents
src/openreliant/	Main application entry point, CLI parser, and installer.
src/engine/	Reimplemented engine modules mirroring original source layout.
src/platform/	Platform abstraction layer: SDL3, Vulkan/Metal GPU backend, audio, and inputs.
src/formats/	Parsers and decoders for StarLancer file formats.
src/tools/sltool/	Command-line asset inspection and extraction tool.
src/tools/tablegen/	Generates static engine lookup tables from the original executable.
docs/	Documentation (see docs/README.md).
ghidra/	Ghidra scripts, symbol annotations, and type maps.

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License

Copyright 2026 the OpenReliant contributors.

• Source code is licensed under the Mozilla Public License 2.0.
• Documentation under docs/ is licensed under Creative Commons Attribution-ShareAlike 4.0.
• Statically linked libraries: OpenAL Soft is licensed under the GNU LGPL 2.1, the part of FFmpeg that decodes the movies, the crew's lines and mods' audio under the GNU LGPL 2.1 or later, FreeType, which draws the outline fonts, under the FreeType License, and Luau, which runs mod scripts and reads mission source, under the MIT License. Portions of this software are copyright © 2026 The FreeType Project (https://freetype.org). All rights reserved. Luau is copyright (c) 2019-2025 Roblox Corporation and copyright (c) 1994-2019 Lua.org, PUC-Rio, under the MIT License; see LICENSE-luau.txt.
• The interface's text is drawn in Newtown, by Roger White, from Roger's Fonts, in the public domain (deps/newtown).
• The runtime shader compiler uses glslang, under its BSD and MIT notices (LICENSE-glslang.txt), and SPIRV-Cross, under Apache 2.0 or MIT (LICENSE-spirv-cross.txt).
• Mods' pictures are compressed for the GPU with Richard Geldreich's bc7enc and rgbcx from bc7enc_rdo, under the MIT licence (LICENSE-bc7enc.txt). PNG files inflate with zlib, under the zlib licence.
• The installer reads the game's cabinet with libarchive, under its BSD licence (LICENSE-libarchive.txt).
• The window, the input and the GPU go through SDL, under the zlib licence.
• The movies' upscale is ported from AMD FidelityFX Super Resolution 1.0, under the MIT licence.