In my preview of Diablo 4, I said I was concerned that frequently bumping into random other players would interfere with the desolate and desperate mood. While you can solo the game, you can't do so without seeing other players in towns and around the open world.

Diablo 4 lead designer Joe Shely and executive producer/Blizzard co-founder Allen Adham tell me that maintaining the right mood is important to them, too, even if an online world is part of the game's vision. Here are a bunch of details about the workings of that world, difficulty levels, and dungeons that came out of my brief interview with the duo:

Because the open world is shared, there are no game-wide difficulty levels. Hardcore (permadeath) mode was mentioned in yesterday's group interview, though.

Enemy levels scale so that friends can always play together, but some areas are meant to be more difficult than others, so players can seek out more or less challenge depending on where they go.

Scaling won't stop you from becoming more powerful by finding better gear, says Shely.

Dungeons are private for solo or partied players. It's only in the open world where you'll encounter the public.

When entering a dungeon, you can select difficulty options "with great granularity."

Areas "relevant to the campaign" are private to you or your party when you first enter. That can change later on, with the world generally changing according to your progression in the campaign.

To maintain the sense that you're an embattled hero in a desolated environment, player populations will change depending on what part of the world you're in. Towns will be the most populous. As you adventure deeper into the wastes, however, you'll encounter other players less frequently. No word on specific numbers.

World events will call players together to fight as a group, but there's no word on specific player counts for those, either.

Shely says it's important to have a variety of endgame activities. One of them is "keyed dungeons." You acquire keys, and then use them to turn a dungeon into an "endgame dungeon" which can be very difficult.

There are five regions, a day/night cycle, and dynamic weather. You can wander where you want, riding mounts to travel long distances.

There is no option to disable seeing other players or an offline mode, but you can solo the whole game if you never feel like grouping up.

We didn't get into specifics about PvP, but apparently there's plenty of time to get those details out there. Even though Diablo 4 is announced for current gen consoles despite new ones coming soon, they say there's still a lot of work to do. I couldn't get any indication of whether that meant one year, two years, or even longer.

I also asked about monetization after launch. Diablo 4 will get expansions. As for microtransactions and passes and that sort of thing, "We won't sell power," said Adham. That's all they have to announce about that right now.

Despite feeling a bit weird about other players popping in and out of my world—even though it does streamline the Diablo 2 experience, I suppose—I had fun trying out Diablo 4. I'll have more from my interview this week.