

I had no noteworthy issues with the Chapter 3 video cutscene.
In the "select microphone" menu in the secret minigame room in Chapter 4, both output and input audio devices can be selected. Selecting an active output device makes it so that the volume of played audio, and not mic sound, controls the gameplay. Selecting an input device, or right-click/cancel, works as expected.

PROTON_USE_WINED3D=1 %command%
Should work flawlessly on modern hardware, needs PROTON_USE_WINED3D=1 on older GPUs

Does not start with Experimental, Hotfix, 9.0, or the 10.0 beta.
Immediately fails to open with "Compatibility tool failed" error.

PROTON_USE_WINED3D11=1 %command%
PROTON_USE_WINED3D11=1 %command%
No performance issues until being at the end section of chapter 1. Consistent stutters occur when being in the last map area. This happens when using default proton version. Switching to Proton Experimental, and setting launch option fixes stutters in that area.

Game works perfectly fine, outside some small issues with switching from fullscreen to windowed.
Switching from windowed to fullscreen sometimes displayed the game only on a quarter of the screen. This only happens when I have display scaling at 125%.
Also, sometimes when switching to windowed got the window "stuck" at the top left of the screen, with no way to move it. Switching back to fullscreen from this state results in the bug above. The only fix I could find is to play the game in windowed mode until I got to a savepoint and restart.

Runs OOB and videos play fine with GloriousEggroll 10.4. Have not tested with other versions.
Game wouldn't launch unless I switched to GE 10-4.

Other than some minor bugs with controllers being detected, it works flawlessly.
The game seems really picky about when you connect the controller. It won't detect the controller if I connect it before launching the game, and it won't detect if the controller disconnects and reconnects for any reason. The only way I've gotten it to reliably connect is by connecting the controller in the main menu, using the keyboard to start the game, and then using the controller from there out.
Some configuration is required - when launching out of the box the game would immediately crash. Swapping to experimental fixed this issue.
gamemoderun mangohud %command%

Funciona perfeitamente com Proton 9.0.4.
Eu não tinha um save da demo, joguei só os capítulos 3 e 4.
Funciona perfeitamente com Proton.

Everything works including video cutscenes. Audio crackling is the only issue.
Some crackling every few seconds

An mp4 video cutscene at the beginning of chapter 3 doesn't play properly but it does not affect gameplay.
have fun!

Proton 10.0-1 works fine in Chapters 1 and 2, but crashes in Chapter 3 as TeeVee tells Mike to play the VHS. All other versions of Proton won't start the game.

Demo save file had to be manually imported.

Saves didn't transfer automatically from the demo. Had to manually transfer the saves between proton prefixes (via command in my Steam guide)
I experienced a few bugs related to input & game stability, but it doesn't seem to be exclusive to Linux and they will hopefully be patched soon. I also had audio issues at first, but they disappeared when I closed background programs.

Works OOTB.
From start to finish, no problems.
game runs perfectly on proton hotfix even after the recent hotfix patch

a bit of CPU overheat despite the low usage, but I think that might be an inherent problem, not with linux, since same happened on windows

Works perfectly
on linux you have to manually move save data from the demo to the main game
other than some save data issues with the demo moving to the main game that are super easy to fix, it works fine

Chapter 3 makes use of FMV video which will not play without the use of Proton-GE. This has no baring on gameplay.

I had to manually copy my save data from the Chapter 1 & 2 Demo over. You can find the save data from the demo here:
Steam Library/steamapps/compatdata/1690940/pfx/drive_c/users/steamuser/AppData/Local/DELTARUNE/
Copy everything in that folder into:
Steam Library/steamapps/compatdata/1671210/pfx/drive_c/users/steamuser/AppData/Local/DELTARUNE/
Now you should have your save data from the demo.
This might have been my own fault because I was copying save data, but I just went to the ingame settings and reset the controlls back to default. After that everything was working.
Proton 9.0 seems to not be working. The following proton versions all worked for me: - GE-Proton10-4 - Proton Hotfix - Proton Experimental

PROTON_USE_WINED3D11=1 %command%
wouldn't boot at all before switching to experimental, now runs better after tinkering than it does on my windows pc with better hardware specs

Window decorations are basically absent; window has a basic blue border (whilst focused) and white, blank top buttons. This is a Proton issue, I think.
Completion files from the demo were not detected, and had to be copied over manually. There are guides on how to do this.
Visible frame drops in some sections of Chapter 3 (I was using OBS at the time, but it shouldn't have been enough to cause that)
umu-launcher is completely borked on my computer (games will not start) for some reason, which is why I'm using Proton Experimental.

Window decorations are basically absent; window has a basic blue border (whilst focused) and white, blank top buttons. This is a Proton issue, I think.
Completion files from the demo were not detected, and had to be copied over manually. There are guides on how to do this.
Visible frame drops in some sections of Chapter 3 (I was using OBS at the time, but it shouldn't have been enough to cause that)
umu-launcher is completely borked on my computer (games will not start) for some reason, which is why I'm using Proton Experimental.

Crashes on cutscene with Tenna in Chapter 3

Crashes before even showing the window
It just crashes pretty much as soon as I click "play" in Steam. I tried it with GE-Proton10-4, Proton 9.0-4, Proton Experiemental, and Proton Hotfix all to the same result. Not sure what's going on to cause this.
I can start the demo just fine, but the main game will just not work for me. Also seems to work fine on the Steam Deck, just not on my desktop PC.

The game runs well. The window, as was the same with undertale, starts in a small window. I used (while focused) ALT+ENTER to fullscreen the window (using GNOME; largely not default settings, you'll have to see if this works for you).

[Chapter 3/4 Release] Did not work on latest Proton, only on GE for some reason. (Also PEAK)
gamemoderun %command%
Does not detect the demo save file (Look at Steam guides for help)

Save files from the demo are not automatically detected due to the full release having a different game ID and wine prefix. To import your saves, copy the folder /path/to/your/SteamLibrary/steamapps/compatdata/1690940/pfx/drive_c/users/steamuser/AppData/Local/DELTARUNE and paste it to /path/to/your/SteamLibrary/steamapps/compatdata/1671210/pfx/drive_c/users/steamuser/AppData/Local/DELTARUNE
If you had save file in demo you have to manualy copy it from demo's prefix to full game's

PROTON_USE_WINED3D=1 %command%
Window not resize-able
After the game opens you may not be able to click on other windows

If only the audio wasn't broken
No Audio except on the chapter selection window

Information
Since Deltarune's Demo and Deltarune have separate AppID's, the save file from Deltarune's Demo needs to be manually transfered over. They are located at, if you installed to your home folder, $HOME/.local/share/Steam/steamapps/compatdata/1690940/pfx/drive_c/users/steamuser/AppData/Local/DELTARUNE
.
This needs to be transfered over to the 1671210
AppID compatdata folder.