The Fallout 4 1.5 patch with Survival mode has been out for about a month now on Steam, but only in beta form. If you're not a beta kind of person, today's your day as the update has gone public.
Survival mode appears aimed at oldschool Fallout fans or just any masochist that enjoys the challenge of a harrowing, realistic experience -- the kind you'd find in a real wasteland. It's especially for you liked the excellent Fallout: New Vegas hardcore mod from developer Josh Sawyer. The key changes here are the removal of fast travel and save anywhere functionality (now you can only save when you sleep), and "increased lethality, diseases, fatigue, danger and more." In short: it's rough out there. If you want to know more, check out our 'Everything you need to know about Fallout 4's new Survival Mode' article.
Other inclusions in the patch: better performance and stability and lots of bug fixes, among other things. Boot Steam to grab it now.