Traverse from one cube room to another cube room with the help of keys

I don’t quite understand your goal. If something moves in the boxes, it must also be visible. So with partially opaque walls, the camera must be in the box or a neighboring box with an open wall.

Maybe this discussion will help you.

How to remove interior faces while keeping exterior faces untouched? - #19 by hofk

see also

BoxLabyrinthCreation3D

BufferLabyrinthCreation3D

DungeonCreation2D