There is a Wikipedia article about this: https://en.wikipedia.org/wiki/List_of_open-source_video_games

It is, however, vastly incomplete, as entries without “reliable sources” get deleted. Mind that linking the source code repository, the steam page, the license file and news about a game going open source are not enough to count as “reliable source”.

I’ll go with “less than 100 reviews”, as with “less than 1000” my list would get really, really long. This leaves two titles in my Steam Library which I think deserve way more attention than they got:

• ComPressure: It’s a Zachtronics-like game, where you build analogue and logic circuits using steam pipes and valves instead of wires and transistors. Its UI is a bit unwieldy, but the game itself is amazing, and it really is a shame that it hasn’t gotten more attention. Also, while there is a paid version on Steam, the game’s source code is available.
• Crown of Pain: It’s a match-3 with RPG elements. That’s basically all that is to it, but it’s a lot of fun.

My top answers are of course Kerbal Space Program, Dwarf Fortress and Stellaris.

However, all those have been mentioned already, so, to add something new to the list: Pathfinder: Kingmaker. It is currently my favourite cRPG.

Edit: Since you mentioned “Great Linux ports”: Kingmaker has a game-breaking bug in the Linux version regarding Gamepad input. However, as long as you play it with mouse and keyboard (as the gods intended - insert PC Master Race meme), the Linux version is working perfectly fine. However, if you plan on playing it on the Steam Deck, you might want to play the Windows build.

And their gamepads for Xbox were pretty good too. Past tense, because those of the Xbox Series X suck (including the “Elite”).

This. I had written a similar last paragraph in my answer below, but decided to delete it before submitting.

I have to suffer Windows at work. No way on earth this sad excuse for an operating system gets anywhere near my gaming PC. I want my gaming PC to be for fun stuff, not use it to torture myself.

First things first: This hasn’t happened to me in ages. I even stopped looking at ProtonDB. Stuff just runs.

However, if a game I buy really wouldn’t run on Linux, I would just refund it (if possible) and play something else. I have a pile of shame that could fill a hundred lifetimes, I really don’t need to play this one particular game.

I’m not sure what problem you are encountering exactly, but switching to another virtual terminal might still work. By default, the virtual terminals are linked to the F1-F8 keys, and the combo to switch from a graphical session usually is CTRL+ALT+Fx.

On that other virtual terminal, you might be able to kill KWin.

and adding it to Game Mode

Wait, waaaaaat? Lutris can do that? Okay, time to download it on my Steam Deck, like, right now. (Okay, not actually right now, I am at work, but today in the evening.)

While gaming performance with the nVidia drivers is often better (I’m talking about FPS alone, not taking into account the card price), the interaction with the desktop environments is way better for AMD, because their drivers are fully maintained as part of open source projects. What I mean are the tools to configure display resolution, and if you are using multiple monitors, their relative positioning. Everything just works. This alone is reason enough for me to strongly recommend AMD over nVidia.

Just to add this: Star Control 2 is not only free (as in free beer), it is free (as in free speech). The open source project is hosted on SourceForge (yes, that still exists), and has a website that is worth checking out: https://sc2.sf.net/

I have been using Linux for more than 15 years and would consider myself a semi-advanced user, but that thing in the screenshot - it scares me.

Android has become such an unusable mess otherwise…

I mean, you can’t even find the option to allow sideloading on my Android TV box without first enabling developer mode…

It really depends on what you are doing with your system…

On my main PC I want the full Linux Desktop experience, including some Gnome tools that require webkit - and since I am running Gentoo, installing/updating webkit takes a lot of RAM - I would recommend 32 GiB at least.

My laptop on the other hand is an MNT Reform, powered by a Banana Pi CM4 with merely 4 GiB of memory. There I am putting in some effort to keep the system lightweight, and that seems to work well for me up to now. As long as I can avoid installing webkit or compiling the Rust compiler from source, I am perfectly happy with 4 GiB. So happy actually, that I currently don’t feel the need to upgrade the Reform to the newly released RK3588 processor module, despite it being a lot faster and it having 32 GiB of memory.

Oh, and last, but not least, my work PC… I’m doing Unreal game development at work, and there the 64 GiB main memory and 8 GiB VRAM I have are the absolute bare minimum. If it were an option, I would prefer to have 128 GiB of RAM, and 16 GiB of VRAM, to prevent swapping and to prevent spilling of VRAM into main memory…

The main issue with btrfs is the RAID 5/6 write hole. If you aren’t planning to use RAID 5/6, it’s fine.

There are some other problems too, but those don’t affect data integrity. The most annoying one currently is that defragmenting breaks reflinks, such that snapshots get turned into full copies, potentially wasting a lot of space. (I have honestly no idea how noticeable fragmentation is on SSDs, and if defragmenting is even worth it nowadays.)

Afaik the --reflink isn’t needed any more with modern coreutils versions.

Anything 2D… Or emulators for old (2D) consoles, or DosBOX…

Sorry, I was a bit confuse. I meant, in the short term Proton is definitely a good thing.

I already asked over at the GoL forums, but I think it’s worth repeating: Does anyone know where one might find a legal download of this game? https://www.mobygames.com/game/3132/rally-championship-international-off-road-racing/

It seems GoG does not have it, and I would really like to play it again - for nostalgia reasons.

Yes and No.

In the short term the answer is a clear “yes”, as it allows players to play nearly all Windows games on Linux without modifications, and game developers to ship their games on Linux without any extra costs.

In the long term it might have a bad effect on the market, as it further helps to cement Microsoft’s control over multimedia APIs, since game developers now have little incentive now to target anything other than DirectX…

In this case it’s a bit weird though, as the game lists Linux as supported platform, but obviously just ships the Windows build with Proton instead of having a native Linux build that uses open cross-platform APIs.

You can also use Steam as a launcher. In Desktop Mode there is a menu entry “Add a Non-Steam game to my Steam Library”. For Windows games, you can just browse to their .exe file. After adding it to the library, you can open the Library Entry’s Properties page, and choose Proton as compatibility tool.

That way you get your non-Steam games in your Gaming Mode launcher.

To get nicer images, there’s a website named https://www.steamgriddb.com/ that also has a small Flatpak tool that you can use in Desktop Mode to set icons/banners for your Non-Steam games.