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.
Sporadic
Clone of Cave Story
An upgraded NXEngine fork for Cave Story with SDL2, widescreen up to Full HD, localization and initial mod support.
Sporadic
Active
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.
Active
Original game image
Original game imageClone of OGame
A single-player browser space strategy game inspired by OGame, built with Vue 3 and TypeScript, with all data stored locally.
Platforms:Web
Stars516
Updated4 months ago
LicenseUnknown
Release2025
Genre: Turn-Based Strategy
Theme: Sci-Fi
Active
Clone of Elite
The cassette version of Ian Bell and David Braben's 1984 Elite source code, reformatted and documented by Mark Moxon, not reconstructed.
Active
Clone of FreeSpace 2
FS2 Open, the FreeSpace 2 Source Code Project, is an open-source build of FreeSpace 2 targeting Windows, Linux, and macOS.
Platforms:WindowsLinuxOSX
Stars487
Updated1 month ago
LicenseUnknown
Release2013
Genre: Action
Theme: Sci-Fi
Active
Active
Original game image
Original game imageClone of One Must Fall: 2097
An open-source remake of the fighting game One Must Fall 2097 with modern networking across Windows, Linux and macOS.
Platforms:WindowsLinuxOSX
Stars478
Updated2 months ago
LicenseMIT
Release2013
Genre: Fighting
Theme: Sci-Fi
Sporadic
Clone of Nanosaur
Pangea's 1998 Mac game Nanosaur, updated with permission to run on modern macOS, Windows and Linux.
Platforms:WindowsLinuxOSX
Stars474
Updated6 months ago
LicenseUnknown
Release2020
Genre: TPS
Theme: Prehistoric
Active
Clone of Elite
The fully documented original Commodore 64 source code for Elite (1985), annotated line-by-line and built into four accurate variants.
Active
Clone of Star Trek
An open-source programming language whose example programs include recreations of classic games like Pac-Man and Tetris.
Archived
Active
Active
Halted
Clone of Cortex Command
CCOSS is the open-source release of Cortex Command's engine under AGPLv3, without game data, requiring the original game and Steam DLLs.
Halted
Original game image
Original game imageClone of Return to Castle Wolfenstein
Official id Software GPL source release of Return to Castle Wolfenstein's multiplayer code; game data isn't included.
Active
Original game image
Original game imageClone of Star Fox 64
A native port of Starfox 64 made by static recompilation, with high framerate, widescreen and mod support. Needs your own ROM.
Stars377
Updated3 months ago
LicenseGPL-3.0
Release2024
Genre: Shooter
Theme: Sci-Fi
Active
Original game image
Original game imageClone of Blake Stone: Planet Strike
BStone is an actively maintained source port of the Blake Stone series, adding high-res 3D rendering, texture upscaling, and 3D audio.
Halted
Clone of Duke Nukem II
Duke 2 Reconstructed is a from-scratch reconstruction of Duke Nukem II's source code from disassembly, producing a byte-identical binary.
Active
Original game image
Original game imageClone of Dune 2
Dune II - The Maker is an actively maintained Dune 2 remake built with CMake and GCC, with documented builds for Windows, Ubuntu, and macOS.
Platforms:WindowsLinuxOSX
Stars364
Updated1 month ago
LicenseUnknown
Release2012
Genre: Real-Time Strategy
Theme: Sci-Fi
Active
Clone of Elite
An open-source space trading and combat simulator with entirely original assets, inspired by the classic game Elite.
ActiveOriginal game image
Original game imageClone of Star Fox 64
A complete matching decompilation of Star Fox 64 (US REV 1.1); not a PC port, and you supply your own ROM.
Stars348
Updated1 month ago
LicenseCC0-1.0
Release2023
Genre: Shooter
Theme: Sci-Fi
Halted
Clone of Star Wars Episode I: Racer
A partial open-source port of Star Wars Episode I: Racer that uses CPU emulation to run the original game cross-platform.
Sporadic
Clone of Quake 2
FTEQW is an advanced, portable open-source engine for idTech games like Quake, Quake II, and III, with servers holding hundreds of players.
Halted
Original game image
Original game imageClone of Doom
id Software's free GPL source-code release of DOOM Classic for iOS, not including any game data, which remains under the original EULA.
Active
Clone of Quadrilateral Cowboy
Blendo Games' official GPL source release for Quadrilateral Cowboy, a first-person cyberpunk hacking adventure built on idTech4.
Active
Active
Clone of Imperium Galactica
A Java reimplementation of the 4X space strategy game Imperium Galactica, bundling its data with Digital Reality's permission.
Halted
Clone of RimWorld
A Unity tutorial project and base-building game skeleton inspired by Dwarf Fortress and RimWorld.
Platforms:WindowsLinuxOSX
Stars325
Updated1 year ago
LicenseGPL-3.0
Release2017
Genre: Simulation
Theme: Sci-Fi
Active
Clone of Cortex Command
CCCP is a community-driven continuation of Cortex Command's development, free and open source under AGPLv3, with an active mod portal.
Platforms:WindowsLinuxOSX
Stars322
Updated3 months ago
LicenseAGPL-3.0
Release2024
Genre: Action
Theme: Sci-Fi
Sporadic
Sporadic
Clone of Doom
A portable, enhanced source port supporting Doom I/II, Heretic, and Hexen, built as cross-platform C++ libraries.
Archived
Sporadic
Active
Halted
Active
Clone of Space Station 13
An open-source, pre-alpha 3D revival of Space Station 13, built in Unity and expanding *beep's original SS3D demo.
Halted
Active
Original game image
Original game imageClone of RoboCop
Compilable, editable disassemblies of 26 NES games that rebuild ROMs identical to the originals.