A new option when you create a new (public?) instance of a world:
-If user is 18+ (account dob), user can check a box to mark the world instance as 18+.
-Similarly, users under 18 can mark the instance as under 18.
-Default can remain all ages as it is now.
When a user is looking at a world they might want to join, the user can tick a box to only show instances that fit their age category (either 18+ or under 18).
Why this feature? It would be
extremely
simple to implement. Has nothing to do with NSFW content. It would be effective and useful for a large majority of users.