Nuclear winter is coming. I don't know if that wordplay worked given the Boston setting for Fallout 4 [official site] seems pretty balmy but you'll have to make your peace with it because it's the best this jetlag will produce. As for *when* it's coming, the answer is 10 November, 2015.
Fallout 4 was the big finale game at the Bethesda E3 conference, with Todd Howard revealing that the studio had been working on it properly for the past 4 years, although design started in 2009, pretty much as soon as Fallout 3 was done. At the event the company showed off a lot of artwork from the game as well as sharing more detail on some of the game's mechanics, systems and setting.
The game begins pre-nukes. There's a character creation section which involves you and your partner staring into the mirror (switching between them is the gender selection option) and giving you a bunch of features to play with. As someone who is notoriously bad at character creation I'm hoping that the way you drag the features with the cursor to resculpt them might make for fewer "OH GOD I WAS IN A HORRIFIC ACCIDENT" protagonists which I then have to explain to people watching me stream. Information given to a door-to-door Vault-Tec sales representative is how you set up your character's traits and so on.
Obviously, as well experiencing this domestic, ice-cold Nuka Cola drenched bliss, you also play in the post-apocalyptic version of the world which begins as you emerge from Vault 111 two hundred years in the future. But it's okay. Codsworth, your pre-nuke robo butler, is still sort of there AND you get a dog to whom you can issue context-sensitive demands.
[The Fallout 4 stuff is from about 1:05:00 in the video above]
Here's a fact about Codsworth - apparently Bethesda has recorded voice lines for 1,000 of the most popular names so you can hear your chosen character name as you play. Obviously this only works if you name your characters things like John and not "You Jerk" or "Bananas Coleslaw" or "Nebuchadnezzar". Or "Philippa", I suspect.
ANYWAY. At this point you're given the freedom to start exploring and doing Fallouty things. Play is first person and third person and the VATS system is back along with familiar inhabitants of the landscape like Molerats, Radscorpions and Deathclaws.
The aspect Bethesda seemed most keen to discuss at the event was the crafting system. The junk you collect as you roam will be useful for that system, yielding crucial materials - handcuffs or a globe converting to screws, for example. With these you'll be able to build and customise your things. On the weapons front there are 50 base weapons and 700 weapon mods (the bladed aluminium baseball bat caught my eye from that section of the conference). That customisability also applies to your power armour.
Then there are the settlements. Other items you craft are used to build up and furnish your own home and surrounding area. Some of that will be prettying up your house but there are also food crops and water pumps to offer sustenance, generators which you can wire up to other items to power them, terminals to govern the activity of other units and defence options like sentry turrets for protecting your settlement from raiders. You can set up bases in various locations and also set up caravans to travel between them.
These building elements were billed by Howard as being optional, by the way, although from what was said I think building up your base attracts NPCs who sell some of the best items in the game so it's probably better to try your hand at doing so.
Oh, and the Pip-Boy is back, because obviously it is. There are some in-game developments such as the ability for it to play games you might come across - I was rather ticked by a Donkey Kong-style game called Red Menace - but it'll also feed into the Collector's Edition. Y'see that will come with a model Pip-Boy into which you can insert your smartphone and use the specially created app as if it were a real Pip-Boy.
But yes, Fallout 4. 10 November.