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.
Halted
Active
Sporadic
Original game image
Original game imageClone of Time Commando
An early-stage, not-yet-playable engine reimplementation of the 1996 Adeline Software game Time Commando.
Halted
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Original game imageClone of Star Control 2
A Windows remake of Star Control 2, built by combining the author's own custom engine, input, and ECS systems.
Halted
Clone of Alien Breed 3D
A rebuild of Alien Breed 3D I for AGA Amiga from the original source, requiring original data files; playable, but development has halted.
Halted
Clone of X-COM: UFO Defense
Halted
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Original game imageClone of Thrust
An SDL-based clone of Thrust, originally an MS-DOS game by Peter Ekberg, now maintained by Dennis Payne for Windows and Linux under GPL2+.
Halted
Clone of Quake 2
An unofficial, software-rendered Dreamcast port of Quake II, running from demo or full commercial game data.
Halted
Clone of Missile Command
A minimalist, about 96KB clone of Missile Command for Linux, Windows, and macOS, made for a demoscene competition.
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Active
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Original game imageClone of Star Fox 64
A fork of the Star Fox 64 recompilation project adding Universal Windows Platform (UWP) support.
Platforms:WindowsLinuxOSX
Stars6
Updated3 months ago
LicenseUnknown
Release2025
Genre: Shooter
Theme: Sci-Fi
Archived
Sporadic
Halted
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Original game imageClone of Star Wars Jedi Knight II: Jedi Outcast
Raven Software and Activision's official 2002 GPLv2 source release of Jedi Knight II: Jedi Outcast, not a third-party reimplementation.
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Original game imageClone of Mega Man 4
A nearly complete disassembly of Mega Man 4 (US) that reassembles to a byte-identical NES ROM.
Halted
Clone of Breach
A port of the Amiga tactical game Breach to the Sega Genesis in 68000 assembly, with tools to convert Amiga level data and a level editor.
Active
Clone of Gloom
An Android and OUYA port of the ZGloom engine for playing Amiga Gloom and its successors with a gamepad.
Active
Clone of Mega Man 3
A static recompilation of Mega Man 3 (NES) into a native PC executable; an in-development preview where boss fights remain untested.
Halted
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Original game imageClone of Phantasy Star II
A disassembly of Sega's Phantasy Star II for the Mega Drive/Genesis.
Halted
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Original game imageClone of Phantasy Star IV
A disassembly of Sega's Phantasy Star IV: The End of the Millennium for the Mega Drive/Genesis.
Halted
Halted
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Original game imageClone of Quake 2
A port of GL Quake II to run under Wayland on the Nemo platform, with no further detail given beyond its name.
Sporadic
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Original game imageClone of Doom
The Linux Doom source converted to SDL3 and 64-bit, with no other changes, for macOS, Linux and Windows.
Halted
Clone of Nether Earth
A PC remake of the 1987 strategy game Nether Earth, packaged here for Linux.
Halted
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Original game imageHalted
Clone of X-COM: UFO Defense
A turn-based strategy game for Win32 and Android inspired by the classic X-COM series.
Archived
Clone of Blasteroids
A simple Allegro5-based asteroids shooter with continuously spawning asteroids, built via CMake with only Allegro5 as a dependency.
Halted
Halted
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Original game imageClone of Phantasy Star
A disassembly of Sega's 1987 Master System RPG Phantasy Star, for educational use.
Active
Halted
Halted
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Original game imageClone of Robotfindskitten
An Inform 6 / Z-machine reimplementation of the ASCII game robotfindskitten, maintained since 2002.
Sporadic
Clone of Another World
An assembly-language port of Another World to the 8-bit Commander X16, requiring the player to supply the original MS-DOS data files.
Halted
Clone of Corridor 8: Galactic Wars
A fan-preserved prototype source archive of the DOS game Corridor 8: Galactic Wars, distinct from Corridor 7 despite similar filenames.
Active
Halted
Original game image
Original game imageClone of MechCommander 2
An unofficial 'HD' project for MechCommander 2, whose README is mostly Microsoft's Shared Source license text rather than a list of changes.
Platforms:Windows
Stars2
Updated11 years ago
LicenseUnknown
Release2015
Genre: Real-Time Tactics
Theme: Sci-Fi
Active
Original game image
Original game imageClone of X-COM: UFO Defense
An open-source MonoGame remake of X-COM: UFO Defense (UFO: Enemy Unknown), originally built in XNA around 2007.