I'm usually a fan of open source games but rarely do they manage to be actually great. People like giving recommendations like Super Tux Kart that haven't aged well and don't play well. What are some open source games that are legitimately good that I've missed?
This one never gets the love it deserves. It's a fantastic turn based strategy game with multiple campaigns and storylines, multiplayer, and campaign design tools. It's an old project (started in 2003, IIRC), but it's still fantastic
Basically, this is Worms but with adorable little hedgehogs instead of, well, worms. Single player is okay, and it has online multiplayer I guess, but the real fun (just like in Worms) is local multiplayer. Also, it has Portal Guns. There's really no downside to this one.
This one's a little iffy. Re-volt was a fantastic R / C racing game with bright graphics, fun tracks, excellent controls, and a killer soundtrack. For good or ill, it was put out by Acclaim, which self destructed in 2004. The Re-volt fan community, however, doesn't know the meaning of the word "quit."
Nowadays, you can join a lively community with regular online tournaments of the game. There's a new cross platform engine called RVGL (that's Re Volt Game Launcher), and metric tonnes of mods and fan content. You still need the original game's assets, though, which is where it's dicey; they're technically abandonware not open source, unless I'm mistaken.
This project's aim is to be Civilization V, but with more abstract visuals, and, or course, free. In short, it's FreeCiv, but Civ V instead of II and a UI from the 2020s rather than the 80s. (Not throwing shade here; FreeCiv is an amazing project that is exactly what it wants to be!)
It's an open world 2D spacefaring game, with a good core story and more being added by the surprisingly-active dev community.
Not without its flaws, but anyway I think it's a fantastic game in its own right. And it's both "finishable" and under continued development & expansion.
OpenTTD: Old transport tycoon game, but really fun especially in multiplayer
Minetest: Minecraft-like voxel game engine, which means there a many different game modes
Beyond All Reason: Great RTS, also great in online multiplayer or with some friends. (Disclaimer: Possible unfree licenses for artwork)
Dwarf Fortress (free but not open source, thanks for telling me that one): not everyone’s cup of tea, but sometimes you just get stuck in it for hours on end
Warzone 2100, from the community project website and not Steam. Some douche just took the code and uploaded it to Steam themself and does a poor job maintaining it.
Thrive is a free, open-source game about the evolution of life.
From the lowly tidepools of your home planet, you will rise to cosmic dominance. At every step, powerful creation tools and deep simulation mechanics will aid your species’ development. Revolutionary Games is the open-source team of dedicated volunteers aiming to make Thrive a reality.
Our team seeks to accomplish two major goals: create engaging, compelling gameplay that respects our players’ intelligence, and remain as accurate as possible in our depiction of known scientific theory without compromising the former.
One Hour One Life is open source, it is a 2D hand drawn survival game where you have 1 real life houre to live from a baby to an elder and contribute to the player-made society in your life as best you can.
You have to pay for an account on the official servers, but i recommend you do to support the development.
Not sure if the dev accepts community patches or not, but the game is public domain license.
Minetest and several others that I play regularly have already been mentioned, so I wanted to shout out a game I've been following and playing for years, waiting for their 1.0 release: FreeOrion
Naev - an open world space exploration game. Cruise the galaxy as a bounty hunter, work as a freighter, enlist in the military, or become a pirate! Lots of ship customization and a huge map with lots of factions.
I haven't played Warsow in years, so I don't know what state the game or community is in. It's a fast paced FPS multiplayer that turned the old bunnyhopping exploit into a central feature iirc.
Frets on Fire! It was the cool open-source equivalent to Guitar Hero. And you know what - it was pretty hecka cool to wield your keyboard like a guitar.
Beyond All Reason if you're looking for an RTS similar to Supreme Commander. I haven't tried playing it in a few years though. I'm sure it's gotten some updates since then.