>>1394251Like 90% of Steam games have DRM that check if the steam client is running and refuse to open if its not. Also closing the client after a game has started will make steam close it.
>>1394200https://youtu.be/WInGPWdhW8c?si=kpFheXZ11fph3yI5I used this method that doesn't use vgui, instead it downloads an older version of the client and disables autoupdate.