I am disappointed with Deep Dungeon

[aesteval]

Is it? People meant that you can do the content solo, not put yourself into the waiting queue. Can I start doing diadem solo (gathering for example) without waiting for or making a group? That would be nice.

You can queue as a partial party from a FC workshop. I don't know if the game lets you go in by yourself though. Even if the game lets you, it's a terrible idea because you're unlikely to be able to attune solo. Going in as a duo definitely works just fine though.