@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, we're using one issue report per unofficially supported game title (in this case, the SDK base), so I've gone ahead and transferred this issue report to https://github.com/ValveSoftware/Proton/issues/5792#issuecomment-4371267000.
proton experimentalx1 2026-05