[quote name='PublikDefender']same difference. what's your point? he was just informing people that if you buy it from impulse/gamestop you can activate it on steam. not every pc game uses steamworks.[/QUOTE]
"Use" and "require" are TWO different things.
"Use" = makes it sound like it's optional
"require" = you have to use it period - like it, love it, hate it, feel different, or whatever.
Sometimes Steam is an extra OPTION -- i.e. buy X3: Terran Conflict from Retail -> you can use that and patch it up so it's DRM-FREE; and you can ALSO register it on Steam (namely for getting DID Mode).
Many times, Steam is NOT optional - as in Deus Ex: HR's case.