The open source gaming scene features a lot of amazing projects, but it is like a mess in a jungle. This article aims to provide a curated list of interesting games, so you have actually more time playing them.
Some developers let you access the source code, which means you can inspect, modify and possibly even compile your own version of it, if you desire so. Unfortunately many of them are very rough on their edges, abandoned or the online modes lack the needed player base to have fun. My goal is to help you finding the gems. For this matter, I searched the web and other lists, read about them, watched videos and decided if they belong to this place or not. I did not play most of them and cannot judge their quality. That is your job.

Windows users can often find an installer in the download section on the official websites. Sometimes ready to go binaries for Linux are also provided, otherwise the repository of their distribution have it or various other places.
Btw, this is part two and a follow up to my previous article Open Source DRM-Free Games. Make sure to check it out, if you didn’t already so.
What is included?
True liberal Open Source is usually defined by the Open Source Initiative (OSI). Not all projects here are strictly conform to it, in example sometimes the game assets and art files fall under a proprietary license, but are needed for compiling. This is not to be confused with the ports and rewrites of engines, to make the original (closed source) games be playable on modern hardware, which are summarized below in a separate list. Also, unfortunately some projects do not offer a Linux build. I don’t know if they are all playable through any compatibility layer or can be easily compiled by yourself.
Games and Engines
Overview
A little compact list out of all titles from both listings. The links point directly to their websites: Annex: Conquer the World, Bos Wars, Colossal Cave Adventure, Cube 2: Sauerbraten, Duck Marines, Dust Racing 2D, DXX-Rebirth, Flare: Empyrean Campaign, FreeCol, FreeOrion, GCompris, Hurrican, Julius, Kobo Deluxe, Liero, Lugaru, M.A.R.S. a ridiculous shooter, Mindustry, NXEngine Evo, OpenClonk, OpenDungeons, OpenJK, OpenMW, OpenRA, OpenRCT2, OpenTTD, OpenTyrian, osu!, Remnants of the Precursors, ScummVM, Shattered Pixel Dungeon, Solarus, Sonic Robo Blast 2, TVTower, Unknown Horizons, Unvanquished, Valyria Tear, VVVVVV, Zelda Classic, ZDOOM
30 Games

We have projects which are inspired by famous franchises and therefore very similar to them, but with their own take on the formula. Then there are even exact replicas in a new game engine, but without the need of proprietary game files. We even have some formerly full commercial proprietary products, of which the code was opened up and given to the community. Off course there are also plenty of other developers starting unique projects, with an entirely new experience too.
Annex: Conquer the World

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Classic top down RTS
Similar To: Glest, Warcraft
Bos Wars

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Classic top down RTS
Similar To: Command & Conquer
Colossal Cave Adventure / Open Adventure

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: 70’s interactive text adventure
Similar To: Wander
Cube 2: Sauerbraten

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Multiplayer arena FPS
Similar To: Quake, Unreal
Duck Marines

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Multiplayer action and puzzle
Similar To: ChuChu Rocket
Dust Racing 2D

Flare: Empyrean Campaign

Genre: Isometric hack & slash action RPG
Similar To: Diablo
FreeCol

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Turn based strategy
Similar To: Colonization, Civilization
FreeOrion

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Turn based 4X strategy
Similar To: Master of Orion
GCompris

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Educational software suite for kids
Similar To: –
Hurrican

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Side scrolling run & gun
Similar To: Turrican
Kobo Deluxe

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Multi directional bullet hell shmup
Similar To: XKobo
Liero

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Realtime tactical artillery 1vs1 combat
Similar To: Teeworlds
Lugaru

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam (price, HD version)
- YouTube
Genre: 3D beat’em up brawler
Similar To: Overgrowth
M.A.R.S. a ridiculous shooter

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Single screen multiplayer combat shmup
Similar To: –
Mindustry

Genre: Sandbox tower defense
Similar To: –
OpenClonk

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Platform sandbox / action adventure
Similar To: Terraria
OpenDungeons

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Dungeon building and management strategy
Similar To: Dungeon Keeper
OpenTyrian

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Vertical arcade shmup
Similar To: –
osu!

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Rhythm reaction clicker
Similar To: Osu! Tatakae! Ouendan
Remnants of the Precursors

Shattered Pixel Dungeon

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Turn based roguelike RPG
Similar To: Dungeon Crawl Stone Soup
Solarus Editor / Zelda: Mystery of Solarus DX

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Action RPG editor / game engine
Similar To: Zelda A Link to the Past
SRB2 / Sonic Robo Blast 2

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: 3D Jump & Run platformer
Similar To: –
TVTower / TVGigant

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Business manager/simulation
Similar To: MAD TV
Unknown Horizons

Unvanquished

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Multiplayer team FPS with strategy
Similar To: Tremulous, Natural Selection
Valyria Tear

VVVVVV

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam (price)
- YouTube
Genre: Precision platformer
Similar To: –
Zelda Classic

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Engine and editor / Action adventure
Similar To: Legend of Zelda
10 Ports and reimplementations – original game copy required

In this category we have complete new rewrites of existing proprietary engines, to make them playable on modern hardware and other operating systems, or even to extend their capabilities. It is still the same, as the original files are used and needed to play. Usually you can buy the original game without a DRM on platforms like GOG.com for a small fee. A few engines have an active community around it, creating awesome new mods and adventures for free; definitely check out ZDOOM for that matter.
DXX-Rebirth

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris (1), Linux Lutris (2)
- Steam
- YouTube
Genre: FPS / Shoot’em up
Original: Descent 1 and 2
Julius

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: City building and management strategy
Original: Caesar 3
NXEngine Evo

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris (look for NXEngine version)
- Steam
- YouTube
Genre: Metroidvania / Platformer
Original: Cave Story
OpenJK / Open Jedi Knight

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: FPS and 3rd person adventure
Original: Jedi Academy and Jedi Outcast
OpenMW

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: 3rd person action RPG
Original: The Elder Scrolls III: Morrowind
OpenRA

Genre: Classic RTS
Original: Command & Conquer, Dune 200
OpenRCT2

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Construction and management
Original: RollerCoaster Tycoon 2
OpenTTD

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Construction and management
Original: Transport Tycoon Deluxe
ScummVM

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Point & click adventures and RPGs
Original: Over 250 games
ZDOOM

- Website
- Linux Flathub
- Linux Snapcraft
- Linux Lutris
- Steam
- YouTube
Genre: Classic FPS / Engine
Original: DOOM, Hexen

Honorable Mentions
Because we cannot get enough, here are some more games to explore. These are not worse or whatever, there are just various reasons why I did not include them in above list.
- Block Attack – Rise of the Blocks: Nice Tetris Attack inspired clone.
- Extreme Tux Racer: Early Linux racing game against the time.
- freeablo: Reimplementation of Diablo 1 engine, needs original game.
- Hale: A turn based tactical combat RPG.
- Magarena: A fantasy card game to play against a computer ai.
- Mr. Rescue: Oldschool looking arcade styled rescue action.
- OpenBOR: Engine to create and play beat’em ups similar to Street of Rage.
- OpenHexagon: Clone of Super Hexagon, but with a level editor.
- Ri-li: Control a cute toy wood engine to collect items in a single screen window.
- rRootage: Vertical bullet hell shooter for Windows mainly boss battles.
- Super Space Invader: A short modern take on the Space Invaders arcade game.
- SuperStarfighter: Multiplayer couch co-op arcade combat.
- Tanks of Freedom: Turn based combat strategy game like Advance Wars.
- The Bub’s Brothers: Clone of Bubble Bobble with up to 10 players.
- Trigger Rally: Arcade style 3D rally racing game.
- UFO: Alien Invasion: New game based on UFO: Enemy Unknown, needs original game.
- VCMI Engine: Reimplementation of Might and Magic 3 engine, needs original game.
- vitetris: Terminal based Tetris clone.
- Word War vi: 80’s style horizontal shmup similar to Defender or Stargate.
- YSoccer: Very similar to the old top down perspective Sensible Soccer series.
I hope you had a good ride into the open source world and found some interesting and new projects to tinker with. If everything provided on this article is not enough for you or you are missing a known title, then checkout my previous article in Open Source DRM-Free Games.
An extremely obscure but very cool, tiny MMO from 1998-2003 called Mercenaries of Astonia can be found at https://brockhaus.org both v2 (the way to go!) and v3
A few people still play v2’s 2006+ offshoot, Aranock Online, too http://www.aranockonline.com
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