Diablo 4 won’t let you experience the game without meeting other players on their adventures, unfortunately.
I said it before, I’m going to say it again. Diablo 4 is going to be something like a live-service title. Mark my words. Why do I say that? Because there’s no option to play without seeing other players running around, doing their own stuff. This breaks immersion, don’t you think? After all, this is an action RPG, but it’s hard to roleplay as a gritty demon hunter when a dude named “IloveChicken” passes you by. That, alongside many other things, makes me think that this is an MMO that they plan to monetize to hell and back.
But, maybe that won’t matter as we get to play alone in dungeons. At least when we’re slaying evil things you don’t have to worry about the immersion-breaking. PC Gamer got Joe Shely, the lead designer of the game to talk about a bunch of things.
As I speculated, there are no difficulty levels that apply to all areas. Your foes scale. So, you can play with your friends no matter the level difference between all of your characters. Permadeath was mentioned, but nothing concrete was said about that. There are some areas that will have more dangerous areas that you can take on if you have powerful enough gear.
All in all, maybe Blizzard doesn’t screw things up with Diablo 4. Maybe they do. At least we can play Diablo 3 with the Reaper of Souls expansion. You can get the PC game keys for both of those games on HRK Game for an incredibly affordable price.