be noted that steam added DRM in 2008 and DRM exist since '90s, one of the first companies to use it was Nintendo, before the 2000 the USA made the DMCA (i think?) 2001, 2003 and 2004 the EU also passed some law about copyright protection(and maybe DRM?) in the early and mid 2008 many companies before valve started to also use DRM (see Spore, assasin’s creed, etc etc) during the later 2008 and early 2009 DRM was also added by EA, Ubisoft and Atari, alonside Valve
be noted that steam added DRM in 2008 and DRM exist since '90s, one of the first companies to use it was Nintendo, before the 2000 the USA made the DMCA (i think?) 2001, 2003 and 2004 the EU also passed some law about copyright protection(and maybe DRM?) in the early and mid 2008 many companies before valve started to also use DRM (see Spore, assasin’s creed, etc etc) during the later 2008 and early 2009 DRM was also added by EA, Ubisoft and Atari, alonside Valve
Steam added DRM at the very start. And it was originally worse until the public pushed back.
You couldn’t play HL2 without online verification through Steam.