People Playground’s developer says malware spread through Workshop uploads and existing mods, deleting personal files, vandalising Steam accounts and uploading sensitive information that could have been used to access players’ accounts.

Its incident recap advises anyone who played September 21–24 to change their Steam password, enable Steam Guard two-factor authentication, review account activity, check for an email from Steam and scan their PC with updated antivirus software. Affected users received an email; those who did not were most likely unaffected, the developer says.

The recap says the latest build is safe to play and cannot run mods. C# mods will no longer be officially supported or hosted on the Workshop. The developer plans a replacement scripting system it says will be safer, though modding will still carry risks. It says the Workshop is likely to return, but when and in what form remain uncertain.