We have a pair of meta tags — tags that do not describe the content of the question, but instead describe some context around the question.
- challenge: indicates that the asker wants the puzzle to be solved. At best this is a synonym of solutions. At worst, this means “I know the answer”, which is purely contextual information — exactly the same question asked by someone who doesn't know the answer wouldn't have this tag.
- solution-unknown: indicates that the asker doesn't know the solution. Exactly the same question asked by someone who knows the answer wouldn't have this tag.
The solutions tag is less clearly bad, but I don't like it much either: most questions here are about solutions to puzzles in one way or another, excluding the few questions that focus on creation or on mechanical puzzle manipulation.