They may technically be considered "Activision" games, as that company currently has the rights to all of them, but the new GOG offers include what you'd think of as Sierra games (Gabriel Knight, Space Quest, Phantasmagoria) Infocom games (The Zork Anthology) and ... oh, Activision games (Interstate '76).
They're all on sale for 60% off this weekend. You can get the whole bundle for $94.89, if you like ... massive, thematically incomprehensible collections.