Digital games distributor Good Old Games (GOG) has added System Shock 2, called one of the most influential games in history to its cross-platform library. In addition to the seminal first-person shooter, the company has also added 10 more titles to its library for the Macintosh, and has made dungeon crawler Torchlight free until 12:59 GMT on June 20 to kick off its summer sale, with daily deals of up to 85 percent off….