Free & Open Source Sci-Fi Games
489 free, open-source sci-fi games — real clones and remakes you can download, inspect the source of, and modify.
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Clone of Cave Story
A from-scratch reimplementation of the Cave Story engine with quality-of-life improvements, requiring the original game's data files.
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Clone of Star Wars: Knights of the Old Republic
An open-source reimplementation of BioWare's Aurora engine, aiming to run NWN through Dragon Age II — no game has full gameplay yet.
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Clone of Gloom (Quake)
An open-source arena shooter blending FPS combat with RTS base-building, inspired by mods like Natural Selection.
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Clone of Unreal Tournament
A reimplementation of Unreal Engine 1 aiming to run the original Unreal and Unreal Tournament using your own game files.
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Clone of Hard Vacuum
An open-content OpenRA real-time strategy game based on Daniel Cook's Hard Vacuum design, with online multiplayer and a map editor.
Platforms:WindowsLinuxOSX
Stars1,071
Updated12 days ago
LicenseGPL-3.0
Release2019
Genre: Real-Time Strategy
Theme: Sci-Fi
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Clone of Duke Nukem II
A reverse-engineered, feature-complete reimplementation of Duke Nukem II in modern C++, with widescreen and controller support.
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Clone of Doom
Crispy Doom is a limit-removing Doom source port with higher resolution, widescreen, and uncapped framerate, staying demo-compatible.
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Clone of Another World
A readability-focused reimplementation of the Another World engine; needs the original PC DOS game data.
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Clone of Artemis: Spaceship Bridge Simulator
EmptyEpsilon is an open-source game that began as an Artemis Spaceship Bridge Simulator clone but has since diverged with new features.
Platforms:WindowsLinuxAndroid
Stars869
Updated1 month ago
LicenseGPL-2.0
Release2014
Genre: Simulation
Theme: Sci-Fi
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Clone of Might and Magic VI: The Mandate of Heaven
An open-source Might & Magic VI-VIII engine reimplementation, currently able to play Might and Magic VII on modern systems.
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Clone of Total Annihilation
An open-source RTS with physical projectiles and smart units, built on the Spring Engine, similar to Total Annihilation.
Platforms:WindowsLinux
Stars827
Updated12 days ago
LicenseGPL-2.0
Release2013
Genre: Real-Time Strategy
Theme: Sci-Fi
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Clone of Artemis: Spaceship Bridge Simulator
An open-source, Artemis-inspired multiplayer spaceship bridge simulator for Linux with Lua-scripted missions.
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Clone of Doom
DOOM Retro is a Windows Doom source port by Brad Harding since 2013, aiming for a dark, gritty, pixelated take on the classic game.
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Clone of Space Station 13
A free multiplayer RPG remake of the cult-classic Space Station 13, rebuilt outside the original BYOND engine.
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Clone of Freelancer
A C# and OpenGL reimplementation of Freelancer for Windows and Linux, requiring an existing Freelancer installation to run.
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Clone of X-COM: Apocalypse
An alpha reimplementation of X-COM: Apocalypse with modding, a skirmish mode and modern resolutions; it needs the original files.
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Clone of Tyrian
An open-source port of the DOS shooter Tyrian that includes the freeware game data and supports networked play.
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Clone of Cave Story
An upgraded NXEngine fork for Cave Story with SDL2, widescreen up to Full HD, localization and initial mod support.
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Clone of Jagged Alliance 2
A community-maintained continuation of JA2-Stracciatella, running Jagged Alliance 2 on modern systems using data from an original copy.