protonscr

DELTARUNE

protonopen appid 1671210Game compatibility - Unofficial
ValveSoftware/Proton#8779 · opened 2025-06-06 by Dal1ster · updated 2026-07-08 · 14 comments · github · game page · search this game
DDal1ster 2025-06-06 github

Compatibility Report

  • Name of the game with compatibility issues: DELTARUNE ("Full Game"/Chapters 3-4)
  • Steam AppID of the game:1671210

System Information

I confirm:

  • [x ] that I haven't found an existing compatibility report for this game. (The only other one was for the demo, this is for the full game)
  • [x ] that I have checked whether there are updates for my system available.

Proton Log is included. NOTE: the log includes me starting the chapter up until the video plays and the issue/bug happens.

Symptoms

When the game tries to load a video file under linux, it causes some color bars to appear where the video would be and "fast forward" it to where the video would end. An example for this would be in chapter 3, theres a vhs styled video for the intro of the character tenna, on windows it plays normally, but on linux it displays the color bars and fast forwards to the end of it with no sound at all. This same behavior also applies to the Billie Bust Up demo, which has a video at the end that fast forwards over everything. It also makes the image of where the video would be a lot smaller.

Reproduction

Install DELTARUNE full game
Set Proton Version to experimental
Start chapter 3 and get up to the point where the video plays
notice the bug/issue of it fast forwarding

steam-1671210.log

DDal1ster 2025-06-06 github

I can also provide a video if that is needed.

Wwaspennator 2025-06-06 github

For me at least on my oled deck, it played the ch3 video with tenna with no issue, so I dunno why it's not playing there on your end

DDal1ster 2025-06-06 github

https://github.com/user-attachments/assets/8a7bd7c4-ec1f-49f1-b911-8a831890f395

Heres an OBS recording of it, i dont know what would cause it though...
And while it is a derivative of arch, it still should be up to date ,i made sure twice over every package was updated before trying again, but its even weirder that it works on your SteamOS compared to CatchyOS/Arch

Ssimifor 2025-06-06 github

it's working for me on archlinux with my amd desktop, tried on proton 9 and experimental. I'm not sure what your issue might be, do you have nvidia-utils installed?

DDal1ster 2025-06-06 github

Actually yes i have it installed

DDal1ster 2025-06-07 github

Is there any options i should look for that might be causing this?

Ssimifor 2025-06-07 github

@Dal1ster try running the following command in your terminal and then running the game again steam steam://unlockh264/

DDal1ster 2025-06-07 github

Should i shut down steam first?

DDal1ster 2025-06-07 github

alright shutdown steam and ran that command and activated the video again, this time on experimental it plays properly, although i still dont understand why it either requires a cli activation or a proton fork in order to run properly...

Ssimifor 2025-06-07 github

@Dal1ster The game uses the h264 codec but isn't currently configured to unlock it, this should be fixed in a few days, but I figured you'd rather play sooner. If you played another game that unlocks h264 then videos would work here, this is why it was working normally for others.

Wwarcode 2025-06-10 github

alright shutdown steam and ran that command and activated the video again, this time on experimental it plays properly, although i still dont understand why it either requires a cli activation or a proton fork in order to run properly...

You might have accidentally disabled Shader Pre-caching downloads, which also includes transcoded media for games using codecs that valve can't include by default due to licenses.

FFlakyBlueJay 2025-08-21 github

IDK if this is the right place to report (seems like each game has its own issue entry) - but Deltarune is one of those games that looks for save data from another game (specifically, the Chapter 1&2 Demo) so it can transfer any existing data to the full version.

Because of each game on Steam being isolated in its own prefix, this functionality breaks when the game is being run on Proton, and Deltarune acts as if I never completed the first two chapters. One can manually copy their save files from the demo to the full game but even then, this behaviour can be cumbersome for casual users, who won't know what they're looking for.

EEtch9 2026-07-07 github

@Dal1ster The game uses the h264 codec but isn't currently configured to unlock it, this should be fixed in a few days, but I figured you'd rather play sooner. If you played another game that unlocks h264 then videos would work here, this is why it was working normally for others.

@simifor is there a way for a proton fork to flag games that need h264 unlock?

Ssimifor 2026-07-08 github

@Etch9 I'm not sure what you mean, but if you run a game, and you encounter a h264 video then /home/<youruser>/.steam/steam/steamapps/<game appid>/ will contain an empty text file called h264-used

Nothing extracted yet.