Runic's president Travis Baldree talks about the vision for the game:
Our vision is to have an MMO that plays as close to single player as we can get it. It will have the same focus on relatively fast action: carving your way through hordes of monsters with a large number of hugely devastating skills. The game has to be solo-able, but players will have to have skills that make them useful in a party and make them work together.
As the game is free-to-play, it will be supported by microtransactions, but Runic isn't going to sacrifice playability for things to sell. "I will never, ever buy a microtransaction item," Baldree says. "I'm that kind of player. And the game has to be enjoyable for me, too. We don't want our monetisation stuff to offer ways to skip the game because the game is boring."
While the MMO won't be out for a while, the original game is only $5 today on Steam.