Half Life 2 works offline just fine. You can even run the exe directly without Steam open. You just cannot compare the two. But yes, if Steam get shut down you obviously cannot download them again. Same goes for games on GOG. You could archive them, but you can also archive games from Steam, it’s all the same.
Still waiting for them to drop Denuvo so I can pirate it. Yes, I am aware there are some old builds out there, but I know what kind of crazy circumvented Denuvo in those. No, thanks.
I enjoy playing older games I missed out on years ago. Recently I finally played Silent Hill 3 and 4 for instance. Now I plan on doing Resi 1-3 and games like it. Other than that my guilty pleasure is League of Legends. I have accepted that I will play it until they shut it down.