Well i probably look dumb now! I don't think i was running it with Proton. Running it with proton PROPERLY, it looks like this (worse!). The entire UI flickers and is black and broken.

The logs are just filled with that same exact offscreen error.
Try an older version of proton, say 4.13. However, it is odd that this occurs. Same happens in Portal 2 Authoring Tools
source sdk 2013 sp mods fail to launch
Issue transferred from https://github.com/ValveSoftware/Proton/issues/9741.
@sylveonsylvia posted on 2026-05-04T09:08:26:
@GermanAizek commented on 2026-05-04T11:26:45:
@sylveonsylvia,
you need to make an issue using template on Source SDK 2013 (https://github.com/ValveSoftware/Proton/issues/5792) or Half-Life 2 (https://github.com/ValveSoftware/Proton/issues/4557) to join to the issue.
Hello @sylveonsylvia, please add PROTON_LOG=1 %command% to the game's launch options, reproduce the regression, and attach the generated $HOME/steam-$APPID.log to this issue report as a file. (Proton logs compress well if needed.) Also, it would be nice to have notes on what happens with Proton 10.0 and 11.0 to reduce the potential timeframe of the regression.
proton experimental: does not launch. says it cant find gameinfo.txt in any sourcemod i try to launch in steam
proton 11: same as experimental
proton 10: launches sourcemods successfully, no errors
heres the logs
proton_experamental.log
proton_11.log
proton_10.log
The 'Setup file 'gameinfo.txt' doesn't exist in subdirectory' issue happens to me too. Proton 10 works fine, 11 and Experimental are broken. Source 2007, 2013 SP and 2013 MP are all broken. Logs for all on Proton 11:
Source 2007: steam-10509932406671147226.log
Source 2013 SP: steam-16099462730414798866.log
Source 2013 MP: steam-11677091221058336806.log
The issue seems to be that Steam passes the path to the mod as a regular Unix-style path in the command line
/home/andrius/.local/share/Steam/steamapps/common/Source SDK Base 2007/hl2.exe -game sourcetest -steam -game /home/andrius/.local/share/Steam/steamapps/sourcemods/fistful_of_frags
Older Proton versions converted this to a Windows-style path themselves, while 11 seems to just pass this Unix-style path directly to the game, which doesn't understand it.
proton experimentalx2 2026-05proton 10.0x1 2026-05PROTON_LOG=1x1 2026-05
Hammer Editor has worked well on Proton, although the grid views are unbelievably slow to update. Does anyone have an idea why?
Edit: The lag seems to be only when i have something selected, or am making a selection box. I can hold Space and move around the grid view fine, it just seems to be the selections that are slow. Also, i am running through Lutris.
More edit: Here's the log.