Steam should really just let you set games not to update without having to futz around with Offline Mode. Refusing updates for specific games is currently possible-but-very-annoying: you need to set “Only update this game when I launch it” and then ALWAYS switch Steam into Offline Mode before launching; if you ever accidentally launch it while online, it will update and Steam won’t let you roll back.
Steam should really just let you set games not to update without having to futz around with Offline Mode. Refusing updates for specific games is currently possible-but-very-annoying: you need to set “Only update this game when I launch it” and then ALWAYS switch Steam into Offline Mode before launching; if you ever accidentally launch it while online, it will update and Steam won’t let you roll back.
I just tested copy/past the folder, to another location,
Then add it as a non steam game and launched it,
Thats work,
I guess, that can be a workaround,
Yeah there should be more steamwide options for this
properly allowing selection of game versions is a work in progress tho :) https://www.gamingonlinux.com/2024/11/steam-gets-new-tools-for-game-devs-to-offer-players-version-switching-in-game/