Here's an interesting video that I think helps explains some of the details of the game, and is game play. Its a bit long but if there's lots of tidbits of info. I'll try to fill in some of those tidbits in case people don't want to watch a 40 minute video
Game play. As word has gotten out, its in essence a MMO survival game. You can choose to go at it alone or not. You can choose to be friendly or not, and likewise everyone you meet up may not be friendly.
There will be no NPCs, so anyone you meet up will be human. Basically you're heading out into the wilderness and all the cities, towns, and locations are berefit of any bereft human. I'm kind of bummed by this, especially since the game is set in West Virginia and the mentality is that that state escaped direct nuclear strikes.
Without NPCs the goal of the game is to kill the mutated monsters to try to get the launch codes to one of the missle sites to nuke a location, this gives you high quality resources but it helps seal up a place that has these flying monsters that are difficult to kill.
Crafting, and base building is a huge portion of the game, so if you're not killing monsters your setting up a home base for yourself. There still seems to be a lot of mystery and intrigue for you to investigate as you move around in the environment, but there doesn't seem to be much side quests, where as fallout 4 has tons of side quests.
All in all, this doesn't sound like a game that interests me much, maybe I'll still get it, but what I like to do with Fallout 4 is missing or at the very least diminished in Fallout 76