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
Sporadic
Active
Original game image
Original game imageClone of F-Zero X
A native PC source port of F-Zero X (N64) with widescreen, 64DD Expansion Kit support and no emulator.
Halted
Original game image
Original game imageClone of Natural Selection
The official GPL source release of Natural Selection, the Half-Life mod by Unknown Worlds.
Sporadic
Original game image
Original game imageClone of Duke Nukem: Zero Hour
A decompilation of Duke Nukem: Zero Hour for the Nintendo 64, buildable into US and French ROMs via a Splat-based toolchain.
Active
Original game image
Original game imageClone of Doom
An advanced Doom-engine source port descended from SMMU, built with SDL2 and actively maintained across major platforms.
Active
Clone of Doom
A community source port enhancing Ultimate DOOM, DOOM II, and DOOM 3, requiring a legally owned copy of DOOM 3 BFG Edition.
Halted
Original game image
Original game imageClone of RimWorld
An early-development fantasy colony sim adding RPG elements like classes and leveling to a RimWorld-style formula, built in C#/MonoGame.
Sporadic
Halted
Clone of RimWorld
A RimWorld mod distributed as a Harmony-patched DLL, with separate builds maintained for each RimWorld version.
Platforms:WindowsLinuxOSX
Stars249
Updated1 year ago
LicenseMIT
Release2016
Genre: Simulation
Theme: Sci-Fi
Active
Original game image
Original game imagePlatforms:None
Stars239
Updated3 months ago
LicenseUnknown
Release2016
Genre: Real-Time Strategy
Theme: Sci-Fi
Halted
Archived
Original game image
Original game imageClone of Doom 64
Doom 64 EX+ is a community-driven continuation of Doom 64 EX, faithfully recreating N64 Doom 64 with modern features.
Halted
Original game image
Original game imageClone of Half-Life 2
Sporadic
Clone of Doom
A pure Java source port of Doom, nearly complete but still missing network multiplayer.
Halted
Original game image
Original game imageClone of Warfare Incorporated
Hostile Takeover is Spiffcode's BSD-licensed open-source release of Warfare Incorporated, with ports for macOS, iOS, Android, and Linux.
Platforms:WindowsLinuxOSX
Stars210
Updated9 years ago
LicenseUnknown
Release2014
Genre: Real-Time Strategy
Theme: Sci-Fi
Archived
Clone of Another World
rawgl is a re-implementation of Another World's game engine, supporting most original platform releases and data files.
Sporadic
Halted
Clone of Cave Story
A fork of NXEngine, the open-source Cave Story engine rewrite, ported to low-powered handhelds and phones.
Sporadic
Clone of Cave Story
CSE2 is a decompilation of Cave Story; this portable branch runs on Linux, macOS, Wii U, 3DS, and RISC OS in addition to Windows.
Sporadic
Halted
Clone of Flotilla
Flotilla is Brendon Chung's official 2010 source release, combining turn-based 3D ship combat with randomized exploration events.
Platforms:Windows
Stars185
Updated3 years ago
LicenseZlib
Release2020
Genre: Turn-Based Strategy
Theme: Sci-Fi
Halted
Original game image
Original game imageClone of Star Raiders
A fully documented, reverse-engineered assembly-language source of Atari's 1980 Star Raiders, rebuilt directly from the ROM binary.
Sporadic
Clone of Otto Matic
An authorized update of Pangea Software's 2001 Otto Matic that runs on modern macOS, Windows and Linux.
Sporadic
Sporadic
Clone of Chasm: The Rift
A free SDL2 recreation of Chasm: The Rift that runs on the original game's data.
Sporadic
Original game image
Original game imageClone of Wipeout
A Dreamcast port of the wipEout Rewrite PSX racing remake, feature-complete and near-60 FPS on real hardware.
Active
Sporadic
Active
Original game image
Original game imageClone of Descent 3
A new engine for Descent 3 built from its 1.5 source release, adding windowed modes, adjustable FOV, and an improved sound system.
Sporadic
Clone of StarCraft
A StarCraft remake built on the open-source Stratagus engine, requiring an existing StarCraft install for game data.
Platforms:WindowsLinuxOSX
Stars156
Updated11 months ago
LicenseGPL-2.0
Release2015
Genre: Real-Time Strategy
Theme: Sci-Fi
Halted
Clone of Abuse
A fork of the Abuse SDL2 port adding OpenGL rendering, high-res images, cheat console, and Xbox 360 controller support for Windows.
Sporadic
Clone of Dune 2
A cross-platform enhancement of Dune II built on OpenDUNE, adding widescreen graphics, multiplayer for up to 6, and fan campaigns.
Platforms:WindowsLinux
Stars154
Updated10 months ago
LicenseGPL-2.0
Release2023
Genre: Real-Time Strategy
Theme: Sci-Fi
Active
Clone of MechCommander 2
An open-source reimplementation of MechCommander 2's closed engine, fixing bugs, with networking left unfinished.
Platforms:WindowsLinux
Stars154
Updated2 months ago
LicenseGPL-3.0
Release2016
Genre: Real-Time Tactics
Theme: Sci-Fi
Active
Clone of Star Wars: Knights of the Old Republic
A from-scratch reimplementation of the Odyssey engine used by both KotOR games, written in TypeScript and run via Electron or browser.
Halted
Original game image
Original game imageClone of Robot Odyssey
A Java recreation of Robot Odyssey I, running on Windows, Linux, and macOS under a permissive MIT-style license.
Halted
Clone of Elite
A Windows remake of Elite built with Allegro and DirectX, reaching Release 1.0 on 22 July 2001 after several betas.
Active
Clone of Outpost
A C++ redesign of Sierra's 1994 colony game Outpost, keeping its core concepts in a more responsive game.
Platforms:Windows
Stars143
Updated3 months ago
LicenseBSD-3-Clause
Release2018
Genre: Simulation
Theme: Sci-Fi
Halted
Clone of Strife
Night Dive Studios' 2020 GPL source release of Strife: Veteran Edition, the official remaster of 1996's Strife.
Platforms:WindowsLinuxOSX
Stars143
Updated4 years ago
LicenseGPL-2.0
Release2014
Genre: Action
Theme: Post-Apocalyptic