Free & Open Source Sci-Fi Games
521 free, open-source sci-fi games — real clones and remakes you can download, inspect the source of, and modify.
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Original game image
Original game imageClone of Space Station 13
A defunct, unfinished remake of Space Station 13 with original sprites replaced by placeholder art.
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Clone of The Colony
The official Apache 2.0 source release of David A. Smith's 1988 Macintosh 3D adventure/shooter, with PC and Amiga ports.
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Original game imageClone of The Operative: No One Lives Forever
Monolith's official 2001 source code release for No One Lives Forever, published for modding the game.
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Original game imageClone of Space Station 13
Griefly is an open-source C++14/Qt remake of Space Station 13, with separate client and server executables for Windows, Linux, and macOS.
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Original game imageClone of Red Dog: Superior Firepower
Preserved source code for the Dreamcast game Red Dog: Superior Firepower, with no assets included and not known to compile.
Sporadic
Clone of Total Annihilation
An open-source RTS engine highly compatible with Total Annihilation's original data files.
Platforms:Windows
Stars123
Updated7 months ago
LicenseGPL-3.0
Release2017
Genre: Real-Time Strategy
Theme: Sci-Fi
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Clone of Even the Ocean
Even the Ocean is Analgesic Productions' open-source narrative platformer about balancing Light and Dark energy to save Whiteforge City.
Active
Clone of Prey
A community source-port integration of Prey (2006)'s SDK with the open-source Doom 3 GPL engine; still visually unfinished.
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Original game image
Original game imageClone of Quake 2
An experimental Yamagi Quake II fork adding Nightdive's Quake II remaster support and other id Tech-era game formats.
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Clone of Star Control 2
A fork of The Ur-Quan Masters HD-mod for Star Control II, adding many extra graphics options and QoL improvements.
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Clone of Star Wars Jedi Knight: Dark Forces II
Gorc is an early-development open-source recreation of the Jedi Knight: Dark Forces II engine, aiming to run its levels on new platforms.
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Clone of Defender
An open-source shooter in the spirit of Defender, built with PortAudio and libvorbisfile for Linux, macOS, and Windows.
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Original game image
Original game imageClone of F-Zero X
A work-in-progress matching decompilation of F-Zero X that builds the US and JP ROMs from your own copy.
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Original game image
Original game imageClone of Gloom
The official source code for Gloom, an Amiga first-person shooter by Black Magic, released as-is with no completeness guarantee.
Sporadic
Clone of Nanosaur 2
Pangea's 2004 Mac game Nanosaur II, ported with permission to modern macOS, Windows and Linux.
Platforms:WindowsLinuxOSX
Stars103
Updated5 months ago
LicenseUnknown
Release2022
Genre: TPS
Theme: Prehistoric
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Clone of Allegiance
Free Allegiance is an open-source project built with Visual Studio and DirectX, split into client, server, lobby, and logic components.
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Clone of Doom
A Doom source port reviving the older EDGE 1.35 engine with modern visuals, easy modding, and support for Heretic and other IWADs.
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Clone of Star Fox 64
It includes no copyrighted assets and requires you to provide a supported copy of the game, either US 1.0 or US 1.1 Rev A, in .z64 format.
Stars101
Updated3 months ago
LicenseCC0-1.0
Release2025
Genre: Shooter
Theme: Sci-Fi
Active
Clone of The Operative: No One Lives Forever
An in-progress cross-platform source port built on the GPL LithTech engine, currently building the engine and No One Lives Forever 2.
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Archived
Original game image
Original game imageClone of Descent II
Parallax Software's original 1999 Descent II source release, missing third-party code so it won't compile as-is.
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Original game image
Original game imageClone of Descent
A browser-playable Three.js port of Descent, bundling shareware Episode 1 and supporting the full game with your own copy.
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Clone of Elite II
GLFrontier reimplements the Atari ST game Frontier, built on reverse-engineered code plus parts from the Hatari emulator.
Sporadic
Original game image
Original game imageClone of Aliens Versus Predator
An SDL3 source port of Aliens Versus Predator Gold for Windows, macOS and Linux; needs the original game data.
Sporadic
Clone of The Operative: No One Lives Forever
A Windows patch for No One Lives Forever that fixes bugs, restores multiplayer and adapts the game to modern resolutions.
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Clone of Doom
A remaster of the 3DO version of DOOM for Windows, macOS and Linux, based on its official source release.
Archived
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Original game imageClone of Space Rangers 2: Dominators
An archived, partially complete open-source engine for Space Rangers 2 that needs files from the "Reboot" release.
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Original game image
Original game imageClone of Star Fighter
The recovered 1995 3DO port source for Star Fighter, released in 2024, differing in several ways from the Acorn original.
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Original game image
Original game imageClone of Tread Marks
Sporadic
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Original game image
Original game imageClone of Return to Castle Wolfenstein
A standalone Android VR port of the Return to Castle Wolfenstein campaign for OpenXR headsets such as Quest and Pico.
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Clone of Dark Reign: The Future of War
A work-in-progress OpenRA mod recreating Auran's 1997 RTS Dark Reign, using content from the free demo.
Platforms:WindowsLinuxOSX
Stars75
Updated3 months ago
LicenseGPL-3.0
Release2018
Genre: Real-Time Strategy
Theme: Sci-Fi
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Clone of Full Metal Jacket
Preserves the complete executable, data, and source of Full Metal Jacket (1995), playable via DOSBox and rebuildable with Watcom C/C++.
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Original game image
Original game imagePlatforms:Windows
Stars73
Updated5 years ago
LicenseUnknown
Release2010
Genre: Real-Time Strategy
Theme: Sci-Fi
Halted
Clone of Gunpoint
Clonepoint is a free, open-source clone of Gunpoint for Linux and Windows, with custom level support via the Tiled map editor.