The latest beta update to Fallout 4 is now live on Steam, bringing a “revamped” Survivor Mode to the game based on feedback received on the previous update. Before you leap into it with both feet, however, be aware that mod compatibility isn't all there, and Bethesda said “we strongly advise players running third-party mod managers to back up saves and disable/uninstall them before opting into the beta.”
We had a look at an earlier version of Survival Mode a few weeks ago, but the short version is that it makes the game a whole lot tougher, with “additional challenges including no fast travel, saving only when you sleep, increased lethality, diseases, fatigue, danger and more.” Two things of note: Characters at the Survival difficulty will appear under a separate character selection filter, and they will not be backward-compatible with the 1.4 version, so if you end up opting out of the beta for some reason, you will not be able to use them. A more detailed breakdown of the Survival Mode changes is available from the in-game help menu.
The update will also make improvements to the third-person camera when players are up against walls or other objects, and fixes a relatively small handful of bugs. Creation Kit and Bethesda.net mod support are still in closed beta, but Bethesda said it hopes to get them into the Steam update soon.
Because it's a beta update, you'll have to take a few extra steps to access it if you haven't already done so. Instructions are included with the update announcement, but it's pretty simple stuff: Right-click Fallout 4 in your Steam library, select Settings, select Betas, then click on “Beta” in the drop-down menu. Wait for it to update, and you're ready to rock: You'll know you've done it properly when Fallout 4 appears as “Fallout 4 [Beta]” in your library.