This is something that should probably be fixed. As I accidentally found out, you don't need the Bronze Key to beat the game. On Level 8, it is possible to teleport to the stairs at the end of the passageway that automatically sends you back a few squares when you go down it, and thus go down those stairs to the "secret" half of Level 9. The code needs to be adjusted to make teleporting there by accident impossible. Hope this helps!