This looks like a bug, if we intend to properly implement Prim's algorithm - we should be happy to punch a hole in any direction, not just the south or east. This possibly explains why the mazes seem unusually dull.
The fix is - we should keep track of cells on the border with any unvisited neighbour, not just one to the south or east. But if the neighbour is to the north or west, it's the neighbour that will change the state of its walls, not us.
This looks like a bug, if we intend to properly implement Prim's algorithm - we should be happy to punch a hole in any direction, not just the south or east. This possibly explains why the mazes seem unusually dull.
The fix is - we should keep track of cells on the border with any unvisited neighbour, not just one to the south or east. But if the neighbour is to the north or west, it's the neighbour that will change the state of its walls, not us.