I'm level 22 as of this post. I've got 6 companions to choose from.Three power armors and 6 settlements. I still haven't been south of Diamond City on the map. But I do have a story mission where I have to go to the glowing sea. At some point I'll venture that way.
Found a Fatman way early in the game. Only had to use it once at the Witchcraft museum and it was pure luck I made it out of their alive even in Power Armor. Early today, did a mission coming out a sewer and I think I saw an alien space ship crash land towards the north between Lexington and Diamond City. Also found out there's something worst and bigger that Death Claws and Super Mutants. That shit said level 55 in the VATS, had to run from that.
This shit has got to be the most dangerous open world experience I've ever played. Death is really around every corner. I like that.