I found a beta key for Salem in my mail, so I went and tried it out. That turned out to be a big disappointment, the version that was available was in a state which I would consider essentially as being unplayable. It was more a proof of concept than an actual game.
So I went a read up a bit more about Salem, and found lots of "previews" lauding the concept, and barely anybody writing about the actual game. I did find a player-created new player's guide, which contained gems like "don't use the official client, it sucks too much, download an alternative player-created client here or here". That just confirmed my impression that Salem simply wasn't in a state yet where it can be appreciated by anyone other than a hardcore fan.
Furthermore I ended up having serious doubts whether I would ever want to play Salem, even in a more advanced state. I do appreciate the "real sandbox" idea from a philosophical standpoint. But practically new player advice like: "The area around the starting zone tends to be void of materials new players need, as other players have already taken them. Run at least 30 minutes away from the starting area before starting collecting stuff." to me doesn't sound fun. Other sandbox games, like A Tale in the Desert, handle the new player experience a lot better than Salem does. As much as the idea of players being able to change the virtual world by e.g. hacking down trees appeals on a theoretical level, as much I would consider such a system unplayable on a practical level.
Does anybody know if Wurm Online is as bad? I hear it "moved out of beta" after six years. I'd like to try a good sandbox game, but I hate implementations of it where "sandbox" means that existing players make the game unplayable for new players. There is no future in that.