How many castle doors can you open?

[Aphaia]

Okay last door I opened was anna/elsa and they are in the village, I another 4,000 and thought stuff it why not go into another door and see who is next to the village and I cant.

I still have to unlock the frozen and the forgotten biome, but was going to do that later, otherwise I have been focused on trying to level people, next I will have to focus on money to upgrade everything.......

What am i missing, why cant I get into the door after anna?

[Essence of Zem]

I think there are only four doors in the castle that can be opened right now. The rest aren't implemented yet. If you look at your Collections screen and the Characters section of it, you can see if you've opened up all of the characters currently available. There are 17 in the game at the moment.

[tmaddox]

I think there are only 4 realms that are available right now. Why can't you go into more? Because the game is early access and it is all that is there so far.

[syzygy027]

Currently only 4 doors you can open, remember it's Early Access.

[Niiro]

Only 4 so far. Anna/Elsa on the second floor is the last door you can open.
Other than that you have WallE, Remy and Vaiana