Hello @bonkmaykrQ, third party Proton builds can not be used with the whitelist. If you test a mainline Proton build and find you have an equally good experience, let me know and we can re-open this whitelist request.

This was tested using the official 5.9 build.

edit: 5.0, my bad.

Hello @kisak-valve, I have tested it one more time just to make sure and I have footage of the game running flawlessly under Proton 5.0-10. The lagspikes are caused by the Plasma compositor, you may safely ignore them.

https://www.youtube.com/watch?v=VL4MouIfcT4

Bug found, closing this until issue #4471 is resolved.

From #4471: ULTRAKILL: crashes randomly on Cybergrind mode. This is the most resource-demanding section of the game, possibly a memory issue but I'm not 100% sure.

Can you clarify if this is new behavior with Proton 5.13 or are older versions of Proton are equally affected? Please add PROTON_LOG=1 %command% to the game's launch options, reproduce the issue, and attach the generated $HOME/steam-$APPID.log to this issue report as a file. (Proton logs compress well if needed.)

I retested using 5.0 and the issue still persisted. The game usually crashes when either the player dies or when too much is going on. The only difference this time is that no crash dialog appeared, I had to manually kill the game.

Proton Log:
steam-1229490.log

Custom launch options were used, pointing to a custom shader cache path. I did not use these during the original 5.0 test when making the whitelist request. Other games that face this same bug did not use these launch options, so imo it's safe to conclude that they are not the culprit.

I've done some further testing and concluded that the crash is caused by player death in Cybergrind mode. Playing Cybergrind mode does not guarantee a crash, a majority of it runs smoothly up until the player dies and the high score is saved.

What makes death in Cybergrind mode different is that while the campaign prompts the player to press R to respawn, dying in Cybergrind mode triggers the creation of a new GUI object displaying the player's gameplay stats. It seems this stat screen crashes the game on Proton.

This, alongside the bug where other games crash sometimes on menus, leaves me to believe this is an issue with how Proton handle's Unity's UI tools

Bug was fixed in the 12/19/20 Update: https://store.steampowered.com/news/app/1229490?updates=true&emclan=103582791466223081&emgid=5127876236496834337

Other games still have this issue

ULTRAKILL is running perfectly in terms of compatibility and stability compared to Windows, the issue I'm running into is that the game runs better on my Intel Integrated GPU than on my AMD discrete GPU.

Using Proton Experimental as i enter it's "Sandbox Mode", the game ran at 71-73 FPS on the AMD card while it ran at 78-81 FPS on the Intel card. On Windows, for the sake of comparison, the AMD card pulled 115-120 FPS and the Intel card pulled 90-96 FPS.

This was not replicated in the other games I tested: Risk of Rain 2 and Endless Space 2 using the same Proton Experimental build and native linux game Counter-Strike: Global Offensive.

System info from neofetch

Proton log from ULTRAKILL running on the AMD card

Proton log from ULTRAKILL running on the Intel card

I am experiencing the exact same window as seen in #4471 however I cannot find a reason for my crash to be related to the Cybergrind (as I am not doing the cybergrind at all). Currently attempting to clear Level 1-4 (Halls of Sacred Remains) and the unity error window continuously prevents me from clearing the level, sometimes as late as completing both sides of the level. I do not know how to access the logs on the Steam Deck and I have found that the crash occurs in both Gaming Mode and Desktop Mode. I am playing on SteamOS 3.4.11 due to crashes that occurred near-constantly back in late November 2023 after the release of Stable 3.5.5. I have been on 3.4.11 ever since and while overall crashes occur still, this is the first time I've had so many crashes with that specific window.

Replying to https://github.com/ValveSoftware/Proton/issues/4406#issuecomment-2508960344

CORRECTION: I meant to say -force-dx9. This workaround should work for other games if you put in the command for appropriate graphics API.

I solved this by adding -vulkan to the launch options. The game now launches consistently without issues.

Replying to https://github.com/ValveSoftware/Proton/issues/4406#issuecomment-2508960344

CORRECTION: I meant to say -force-dx9. This workaround should work for other games if you put in the command for appropriate graphics API.

I solved this by adding -vulkan to the launch options. The game now launches consistently without issues.

As an addendum, running the game borderless through the launch options was also required to make it launch consistently.

Apologies if this isn't the appropriate place or manner to report this.

The game launches and runs very smoothly, but I run into a performance drop when I do very specific, undemanding actions (most common are using the saw on the sawed-on, charging a piercing shot with the revolver, or other alt fire actions). This happens on every build of proton I've tried (9, experimental, hotfix, GE custom). Verifying the files and uninstalling the game do not fix the issue. It is unaffected by use of wayland/xorg, vsync, framerate cap, psx downscaling, and fullscreen.

My pc specs and info (password: ultrakill)

Occasionally, the bug will miraculously fix itself and I can do those actions without stutters, but it normally comes back within a few minutes.

I've not seen anyone else with this issue.

@isacubes I played around the sandbox for a bit and the game has integrated a hitstop system based on the damage, timing and number of enemies your attack targeted. Could it be that you're seeing this and interpreting it as lag?

https://github.com/user-attachments/assets/9ffdf2d9-959b-4f96-a71d-8adc7ee93762

Attached a video where you can see the hitstop but the framerate doesn't actually dip when this happens.

Is this what you're seeing or something more severe? Are you using anything to keep track of your framerate?

@simifor What I am getting isn't hitstop. The lag I get is genuine lag and it occurs when there are no enemies in a level. After about ten minutes of playing, I see effects demonstrated in this video. The steam fps counter reports a drop.

The oddest bit is that before the bug happens, every action in this video runs with no drop whatsoever. Once it starts, it only goes away after rebooting my pc.

@isacubes unfortunately haven't seen anything weird here. 30 minutes going through missions another 30 in the sandbox and the worst I saw while engaging on right click was shaving a handful of fps from the cap (going down to like 238 fps, briefly if the cap was 240, or 285 if the cap was 288), no big degradation like can be seen in your video. Is there anything special to where you have the game installed or its filesystem? have you tried using something like mangohud to monitor cpu/gpu/memory usage in real time to see if anything there looks off when performance goes down?

@simifor Sorry to get back so late. I was busy, but I still have the issue on the latest version of the game after the update. The game was installed on an NTFS drive at some point, but I very quickly moved it to my main drive (ext4) in hopes that it would help. Mangohud shows that my GPU and CPU load actually decrease when I get the bug. My memory usage is fine (I was monitoring top). The game just. Decides it wants to slow down for a second. I don't know what's going on.

https://youtu.be/XCyCJmOvwmQ

Well, since the 16c patch that released about a week ago, my issue hasn't come up after a few hours of playing. They mention this line in the patch notes for the version:

I suspect that (in tandem with some other issue that was causing the warnings to be printed) was the issue for me and it wasn't a proton-related thing, unless proton noticeably slows games when printing to the console. I suppose I could try running the old version of the game through the console to see if it was printing anything there.

This is my first time reporting an issue on github, so apologies in advance for any mistakes.

Compatibility Report

• Name of the game with compatibility issues: Ultrakill
• Steam AppID of the game: 1229490

System Information

• GPU: Intel HD Graphics 4000
• Video driver version: Mesa 25.0.1-arch1.2
• Kernel version: 6.13.7-arch1-1
• Link to full system information report as Gist: Link to system information and link to steam runtime diagnostic
• Proton version: 9.0-4

I confirm:

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

Symptoms

I am trying to play Ultrakill on my t430 thinkpad on linux using proton 9.0-4. Knowing that the usual DXVK which is used in proton wouldn't work with the Ivy bridge processor due to a lack of Vulkan support, I put PROTON_USE_WINED3D=1 in the launch options to use the OpenGl-based wined3d. While it is technically playable, the main problem is that graphical glitches occur, which can be seen in the attached screenshots. In the screenshots there is an excess of blue where there shouldn't be. I have also seen graphical glitches in other 3D games using wined3d.

Reproduction

1. Launch Ultrakill with the launch options "gamemoderun PROTON_USE_WINED3D=1 PROTON_LOG=1 %command%" and with proton 9.0-4 enabled.
2. Load up any level using 3D graphics.
3. See that there is a lot more blue than there should be (as seen in the attached screenshots).

Proton logs:
steam-1229490.log

System Information

• GPU: ASUS RX 7600 XT 16GB
• Video driver version: Mesa 25.2.6-2 from CachyOS repos
• Kernel version: 6.17.5-2 (CachyOS)
• Link to full system information report as Gist: Steam System Report
• Proton version: experimental

There aren't any major issues on my system, although after 1 or 2 hours of gameplay it starts getting a bit choppy. I don't know if this is either an Ultrakill issue or a Unity issue, or even a Cachy issue, but I suspect it's just some problem with the game leaking some memory after a while (many Unity games suffer from this).

@thebashforkbomber can you attach proton logs? a file called steam-1229490.log will appear in your home folder if you add the following to the game's launch parameters: PROTON_LOG=1 %command%. And it's worth mentioning if you've tried several proton versions.

There's some visual bugs with the new update that's been added that appear to be Linux-specific, some discussion here. TL;DR: theres a door in 8-3 required for progression that, when opened, will render all geometry invisible, making the rest of the game unplayable.

I managed to fix it for myself, but it was a fix I'm afraid is highly specific to me, so I felt it worth posting here in case anyone else has any input on this issue.

There's some visual bugs with the new update that's been added that appear to be Linux-specific, some discussion here. TL;DR: theres a door in 8-3 required for progression that, when opened, will render all geometry invisible, making the rest of the game unplayable.

I managed to fix it for myself, but it was a fix I'm afraid is highly specific to me, so I felt it worth posting here in case anyone else has any input on this issue.

Strangely enough, this never happened to me. I played the new update without any visual bugs.

@thebashforkbomber can you attach proton logs? a file called steam-1229490.log will appear in your home folder if you add the following to the game's launch parameters: PROTON_LOG=1 %command%. And it's worth mentioning if you've tried several proton versions.

I solved this, the issue was fgmod.
Simply removing the launch options was enough.