That specific badge is for game ownership. I believe it's possible for games to be added to your account automatically in some cases (like an HD version given out for free to existing owners) which could unlock the badge without user intervention.
>or could this person have shared a steam account?
That specific badge is for game ownership. I believe it's possible for games to be added to your account automatically in some cases (like an HD version given out for free to existing owners) which could unlock the badge without user intervention.
>or could this person have shared a steam account?
Definitely possible as well.