Counterpoint - the launcher window does not work for me - it just shows whatever was drawn on the steam window and does not accept input.

Monitor: W541 laptop display ( 15.6 in, 1920x1080 )
Display driver: i915 ( I guess)

Also

$ rpm -q llvm Mesa
llvm-6.0.1-1.1.x86_64
Mesa-18.1.5-204.2.x86_64

launcher did work once for me, got into game and started a match.
Now when I start the launcher it just copies the background where it opens.
I can move it around and click on links, but I have a hard time finding the play button.
system information

I had an issue with the flatpaked version, but it has since been fixed by the Steam flatpak mainainer.
It turned out to be a game problem, where long paths would prevent the launcher from working correctly. Reported here.

Below is the obsolete original report.

Doesn't work great for me, at least on the only computer I can try for now.

Arch Linux, i5-7440HQ, three monitors (same on one). Mesa 18.1.5 as provided by the flatpak runtime I am running steam from. Kernel 4.18.3.

• When I tried it on Proton launch day, and Sins would crash after clicking "play" on the launcher
• After today's last update, the game instantly starts complaining about not being able to find gamedata.dat, which is there. I even checked the game integrity.

Manually going there and running the proton command (with the right env) doesn't help.
I should note that after the last update, steam actually installed the prerequisites before launching.

Update: It works perfectly if I replace StardockLauncher.exe with Sins of a Solar Empire Rebellion.exe (renaming the latter as the former). Still unsure why the launcher complains about gamedata.dat.
I can also alt-tab out and back in, although I have to wait a few seconds with a black screen before the game appears again.

After the update I get the same experience as @thunder1410 - game seems to work fine, but the launcher screen copies whatever was rendered on the screen. In Gnome, if I press the start key to show all windows, the correct graphics are shown, but as soon as the window gets focus it reverts to the old graphics.

Input is accepted though so I can eventually manage to click on the play button and start the game.

It is working on Debian 10
I Use Mate Desktop.

My Specs:
Distro Debian 10
Driver: NVIDIA Corporation GeForce GTX 1070 Ti/PCIe/SSE2
Driver Version: 4.6.0 NVIDIA 390.77

Installed everything from Debian repository or default, I have not added any extra config or parameter.

Here is the link to my Steam system info:
https://gist.github.com/snarvaezsoft/dd0a970ce0b9ba8ed19a6c91022d2a50

The game works out of the box for me, also does the launcher. Performance is similar to Windows and I couldn't see any difference. Online play works as well.

Proton: 3.16-4
Sysinfo: https://gist.github.com/NoXPhasma/9ed85e6b0602b656c812acd013ee121f

So the launcher refuses to appear for me out-of-the-box. It shows correctly in the activity window but clicking on it just produces nothing using game's default Proton and Proton 16.5.

https://gist.github.com/byte1024/e11ee2703ad2bc8037747ff5ccd93408

For reference, can bypass the launcher by using launch option
/nolauncher
since it wasn't said here. The game itself starts fine.
.
.

Hello @byte1024, please add PROTON_LOG=1 %command% to the game's launch options and drag and drop the generated $HOME/steam-$APPID.log into the comment box.

Yeah, I was looking into that already lol :+1: (busy with stuff)

steam-204880.log

Noticing some odd things here:

78213.135:0008:002b:warn:module:load_builtin_dll cannot open .so lib for builtin L"Steam2.dll": /home/linux64/.local/share/Steam/steamapps/common/Proton 3.16 Beta/dist/lib/wine/steam2.dll.so: cannot open shared object file: No such file or directory
78213.135:0008:002b:warn:module:load_dll Failed to load module L"Steam2.dll"; status=c0000135

78213.135:0008:002d:warn:debugstr:OutputDebugStringA "Performed current game fixup as unable to find location any other way!"
78213.135:0008:002d:trace:seh:raise_exception code=40010006 flags=0 addr=0x7b43c6bd ip=7b43c6bd tid=002d
78213.135:0008:002d:trace:seh:raise_exception  info[0]=00000047
78213.135:0008:002d:trace:seh:raise_exception  info[1]=00441c68
78213.135:0008:002d:trace:seh:raise_exception  eax=7b42952d ebx=7b638ff4 ecx=00000000 edx=01b2eb34 esi=01b2ebd8 edi=01b2eb38
78213.135:0008:002d:trace:seh:raise_exception  ebp=01b2eb88 esp=01b2eb14 cs=31300023 ds=1b3002b es=1b2002b fs=f7c50063 gs=1b3006b flags=00000216

78213.560:0008:003a:warn:debugstr:OutputDebugStringA "Window on screen fully"
78213.560:0008:003a:trace:seh:raise_exception code=40010006 flags=0 addr=0x7b43c6bd ip=7b43c6bd tid=003a
...
blah blah

Did a re-install to make sure nothing happened there. Still no dice.

I see there's more problems listed in the log though some could be of no consequence perhaps.

78213.299:0008:002e:fixme:bcrypt:key_asymmetric_verify GnuTLS does not support algorithm 11 with hash len 48
78213.299:0008:002e:fixme:crypt:CNG_VerifySignature Failed to verify signature: c0000002

78213.144:0008:002e:err:winediag:SECUR32_initNTLMSP ntlm_auth was not found or is outdated. Make sure that ntlm_auth >= 3.0.25 is in your path. Usually, you can find it in the winbind package of your distribution.

Fixed/check on Fedora by $ su $ntlm_auth -V and follow install prompts (part of samba-winbind-clients). Possibly of no real consequence.

All right, the flatpak issue seems due to the fact that the launcher doesn't support arbitrarily long path names (the limit seems to be ~127 chars): https://github.com/flathub/com.valvesoftware.Steam/issues/253

Now, the launcher has a strange behaviour on KDE plasma/Wayland, which can probably be linked to the invisible launcher issue.
Most issues seems to be from people using Gnome Shell (Gnome 3, I suppose). However, at least one person (@thunder1410) seems to have this issue under X.org as well (Gnome 3 now defaults to Wayland).

When launching under plasma/X.org, I have no issues. However, under Wayland, the window decorations (the blur/shadow that normally appears on the side of the windows) overlays the whole window, and stays above the other windows, stealing clicks.

Screenshots:

• of the "window" below:
  
• of the window and its overlay
  

Note: telling spectacle (the screenshot tool) to only capture the active window produces an image that only contains the blur.

Proton 16.6 allows the launcher to work for me now. Had a feeling it might according to the change log :+1:

A quick test pre-16.6 confirms it not showing up (so no it wasn't a recent Fedora package update or anything)

:-1: and it had the problem again...

:+1: Re-installing the game with 16.6 in use for all games... and now working again. Interesting....

(switching Proton version, rebooting didn't fix, but the above did in this case)

...and back to not working lol :-1:

Paths inside Steam Flatpak were shortened to allow more things to work out of the box. Complete fix-up for existing deployments may require a manual step that can be checked from related issue. New installations should have the expected shorter paths that look similar to native Steam.

No matter what version I choose, after a new installation it shows the Launcher once but then crashes. Tried several different Proton Versions, reinstalls and so on. Every next start the launcher is invisible. I can still get the game to start by clicking the invisible Play button but the game crashes.

Sysinfo: https://gist.github.com/NoXPhasma/0c4275264cc40b269b56051a7a53a2c2
Proton Log Proton 3.16-4: steam-204880.log
Proton Log Proton 3.16-6: steam-204880.log

Either something changed on my end or with the Steam runtime (Latest Steam Beta). Anyway, it's broken for me now.

update
After verifying the game data, the game starts up fine now, which is weird, as I've reinstalled several times. However, the launcher still does not appear.

Works for me. Worked flawlessly for around 8 hours of playtime. (The only issue I had was joining a multiplayer game we loaded from a save, but this seems to happen on windows as well).

@NoXPhasma, have you verified it couldn't be due to some leftover config? Doing domething like verifying the game gache/reinstalling, and deleting steamapps/compatdata/204880/

To keep the answer method simple, I guess you can :+1: this message if it works for you, and :-1: if it doesn't.

Thanks,I'll give a run thru.

Compatibility Report

• Name of the game with compatibility issues: Sins of a Solar Empire: Rebellion
• Steam AppID of the game: 204880

System Information

• GPU: GeForce GTX TITAN Black
• Driver/LLVM version: 4.6.0 NVIDIA 465.31
• Kernel version: 5.12.14
• Link to full system information report as Gist: System Info
• Proton version: experimental-6.3-20210709

I confirm:

• [X] that I haven't found an existing compatibility report for this game.
• [X] that I have checked whether there are updates for my system available.

Symptoms

The game seems to crash within a minute or two of starting or loading a game with a mod (such as STA3 or SotP) loaded. There is no error reported or indication of what the issue is that causes the crash, even when running the Dev executable. The game simply shuts down. This is regardless of whether you're actually playing or not. I have started a game, paused and minimized the game, and still had it crash a minute or two later.

This was tested with both the STA3 and SotP mods. The crashing was consistent with both, whether the game is paused or not. The base game seems to be stable (though I have not played it too long that way), but it isn't nearly as resource intensive as these mods are. The crashing seems to occur more frequently and quickly with higher resource utilization, sometimes not even letting the game start after the loading screen.

I have ran Sins with STA3 stably in the past. However, Sins and Proton have updated since then, so it's hard to tell if Sins introduced an issue or there was a regression with Proton. The mods work on Windows, so it seems unlikely to be issues with the mods themselves (they're just game assets, not DLLs or other code objects that might introduce issues associated with Proton being a compatibility layer). It could be related to base game DLLs associated with loading mods, but that's a part of the base game itself.

Reproduction

• Install Sins of a Solar Empire: Rebellion
• Start game and select Options>Mods
• Select Show Mod Path
• Shut down game and extract a mod like SotP or STA3 to the path ~/.local/share/Steam/steamapps/compatdata/204880/pfx/drive_c/users/steamuser/My\ Documents/My\ Games/Ironclad\ Games/Sins\ of\ a\ Solar\ Empire\ Rebellion/Mods-Rebellion\ v1.85/
• Load the game again, which loads the mod. Start a game and observe it crashing within a few minutes

steam-204880.log

I was able to get Sins with mods to work by adding a DXVK_CONFIG_FILE with the following content:

d3d9.evictManagedOnUnlock=True

For others wanting to test this out, you can execute the following command to generate the file:

echo "d3d9.evictManagedOnUnlock=True" > $HOME/.steam/dxvk.conf

Then setting your launch options as follows:

DXVK_CONFIG_FILE=$HOME/.steam/dxvk.conf %command% /nolauncher