A few months ago, Telltale joined the DRM-free movement at GOG.com with 3 of their best series, Sam & Max Save The World, Sam & Max Beyond Time and Space, and Tales of Monkey Island.
Now two more Telltale series are available DRM-free on GOG.com: Sam & Max: The Devil's Playhouse and Back to the Future: The Game.
Each of these releases contain bonus features, like the soundtracks of the first two Sam & Max seasons (still no Season Three soundtrack, not even in digital form), developer commentaries, animated shorts (Wallace & Gromit's Cracking Contraptions and an unknown short with Season Three - perhaps Our Bewildering Universe?), and more.