The hammock is a great idea so smaller "secret playroom" areas. This kid’s bookshelf opens to a secret reading nook. A SECRET READING NOOK. I would’ve never left. (from Everything About Secret Bookcase Doors)
A bedroom hides behind this bookcase and is accessed through a secret door.
Sliding Shelving: Sliding bookshelves as lair doors.
IKEA - JULES, Child's desk chair, pink/silver color, , You sit comfortably since the chair is adjustable in height.