^ English keyboards don't tend to have umlauts unfortunately.
This is interesting news though, especially as Grona Lund already have a haunted walkthrough attraction by the stage / ice cream shop (called Spokhuset). I wonder if that one will be staying, or if this is just a re-theme of that. It would be weird to have 2 year-round actor-led scare attractions, and I can't imagine where they're going to find the space to build something new!
I've done some research, and the Swedish wikipedia does say that Spökhuset is closed now, and that the new House of Nightmares will follow it up. Shame I never got to do Spökhuset, but if it is indeed dated, then it's good that it will be followed up by (hopefully) something better.