What is your favourite Open-Source game?

Battle for Wesnoth - a turn based tactics game in a fantasy setting. It's also available on Steam and itch.io. Coincidentally, version 1.18.0 was released yesterday.

Roguelikes: DCSS, Shattered Pixel Dungeon, Nethack

Right now I'm basically playing Beyond All Reason almost every evening. It's a game in the Total Annihilation "tree" of games. A massive scale RTS. I previously played Supreme Commander and Planetary Annihilation, both of which are also inspired by Total Annihilation, but I have to say that BAR is really better than both of them. I almost can't believe it's an open source game. It's still in alpha, but it's been way more stable than most AAA games I've been playing recently.

I've gotten all my friends hooked on OpenTTD multiple separate times

Endless sky. You start off with a single spaceship and fly around the galaxy trading, fighting pirates, and buying/capturing more ships. The devs are still regularly adding new content too.

Unciv is a Civ 5 remake with simplified graphics. Its a lot of fun but the AI is brutal.

Does DOOM count? It's been officially open sourced recently, even though it was already treated as such for decades.Either way, I can't stop playing it, there's 30 years of user created content to go through.

Battle for Wesnoth. There's several FOSS games that are pretty good, but BfW I've played the most.

In my AP Computer Science class in high school, every now and then our teacher would give us a free day. We would sit around playing Unreal Tournament on the LAN.

At one point the teacher decided he wasn’t comfortable with a game with guns in class.

So…I got everyone to install Cube, the open source first person shooter. Specifically a copy of it where I had removed all of the gun models. So we just ran around punching and bullets would fly from our fists. Or, in the case of the rocket launcher, an exploding sofa would fly from our fists.

I don’t know if I would call it my favorite, but we had a lot of fun with it.

Mine is Mindustry too

OpenTTD is also nice

Someone on lemmy a few months ago mentioned this rts beyond all reason. Since then I've easily put 100 hours in. The game is so dam fun.

Another great one is Osu

openttd is great

Apart some of the already mentioned (mindustry, 0ad, beyond all reasons, zero-k), also minetest (minecraft), destination sol.

l've tried hege wars (worms clone) but found it meh. Sometimes supertux.

CDDA probably. One of the more comprehensive zombie survival experiences

0AD, so good

Nethack. I remember playing it at university 30 years ago when it was text only. Amazingly, there is a version available for android and its fucking addictive.

Xonotic

Super Tux and Super Tux Kart

Not enough shout outs for Super Tux Kart soccer mode. Getting a group of friends playing that is awesome

Nethack.

I play DDay Normandy, a quake 2 mod

OpenRA d2k

Minetest

Veloren

Fun games

One of my favorites recently has been playing MineClone2 with some extra mods (can't remember which) through Minetest.

I've been boycotting minecraft since the news of chat reporting potentially coming to Java and MineClone2 is such a good replacement. Biggest gripe I have is not being able to get any of the mods that add sprint to work. Pretty much the only feature not available in MineClone2 (as far as I'm aware) from minecraft that I actively miss.

More recently, I'm a fan of shapez (shapez.io) for my recommended daily allowance of factory building gaming.

Going back further, I have a soft spot for Ri-li, a nice little game about toy trains with very charming music! It was this which set me on an adventure with the mod tracking scene. A surprising amount of open source games use them, it feels like open source music!

Reminded me also of Alex the Allegator 4, a very original 2D platformer

mindustry. I've kinda quit playing games. But still play mindustry on my ipad. :)

I like Ltris, Gweled, and Frozen-Bubble. I like simple games. I wish there was a good pacman for Linux too.

Open RCT 2

Doom, or, gzdoom! You can use it to play the original Doom 1 and 2 games with modern mouse and keyboard controls on HD displays. And there's an endless number of fan made level packs to try.

As for open source AND free / open resources, there's Freedoom 1 and 2. I occasionally play them, they're fun, but a little lacking in stage design.

Sauerbraten

What! Mindustry is open source!? Makes me love it even more

minetest is pretty cool. Highly decentralized which is nice. Very flexible, it's just a game engine essentially.

I like Simutrans, which is basically an OpenTTD competitor with more complexity but an uglier interface. Sadly development on it has been fairly slow, at one point there was a one-way road patch but it’s since been abandoned.

Morrowind with vanilla OpenMW

Probably the Ur-Quan Masters.

Chess

There are a lot of great responses on here! I've been playing (at least until my steam deck shit the bed two days ago) around with OpenRA and Minetest.

Star Ruler 2, the company closed down and open sourced the game, it's a space 4X real time, has pretty good fleet combat and u can design ships, i think wasn't popular because the resource management and card system is a bit weird and harder to understand than other strategy games, but pretty fun after u get used to it...

Fellow Mindustry fan!

Veloren all the fucking way

Go / Baduk.

However the white stones are severely overpowered, and the devs refuse to do a rebalance since around the last 4000 years!

Shattered pixel Dungeon fancade and IDK if it counts but fightcade.

Space Station 14

Angband

Cataclysm: Dark Days Ahead

I used to play Tremulous. That was a blast. Very clever game.

For years I've played bzflag. It's a 3d tank battle game with a variety of play methods (capture the flag, soccer, -em-up, etc).

Other than this, there was once some kind of space opera with combat, politics, and other game functions. I can't remember the name now.

Xonotic is really fun if you enjoyed Quake 3 and Unreal. Has an active community as well. Beyond All Reason is a pretty polished RTS using Spring engine.

I hate that Tales of Maj'Eyal is my favorite Open Source game. I hate that a new expansion is coming out soon and I will instantly buy it and play it and hate myself. Check it out!

OpenTTD and Widelands are also pretty cool.

Mine would be Thrive, not so much due to its current gameplay, though it is okay, but moreso due to an unwavering commitment to a vision. It has gone on for years and is essentially a scientifically close to accurate version of spore. They have almost finished the single cell stage and are working some on the transition to multicellular now as I understand it. I find it to be an impressive project as it started from the disappointment with spore and has evolved into something that I would genuinely suggest as a learning tool in middle school biology class.

Neverball is a fantastic ball-in-a-maze (Monkey Ball) OSS game

I played Warzone 2100 for a long time. It isn't as good as Total Annihilation (nothing is), but it had some interesting component-based units.

I should try Veloren some day. It seems very interesting.

Unciv

These suggestions rock, I guess my weekend is set!

openarena?

Project 1999 and Project Quarm. Emulators of EverQuest, which was released in 1999. Official EverQuest is still going strong 25 years later, but the emulator developers (the are several projects) have an agreement to run their versions of the game.

I'm playing Project Quarm version now and spend way too much time on it.

How is Linwarrior 3D? Has anyone played it? It claims it's an open source game similar to MechWarrior 2.

I've had a lot of fun with Brogue.

Stalker anomaly 🥸

/s Forcefully open sourced

Some of the assets still come from the original game, but OpenRCT2 is wonderful.

Jason Rohrer's stuff is pretty famously impressive, and a lot of it has been OS historically.

I spent a lot of time on Crawl Stone Soup, and actually got to the orb run once.

Antimatter dimensions is an idle game that recently became open source