Paperhouse?

It's got many similarities in terms of tone and atmosphere. Both being set within the imagination of a young girl, and much takes place in a barren-looking setting, but the plots are quite different.
Both great though!

We've met before, haven't we?

You probably won't be able to read this, but on the off-chance you ever do find it, I wanted to think you for asking this question! Because of you, I found my new favorite movie, Paperhouse! :D