The Doctor cheat is a registry edit that, in Creatures version 1.0.2 and above, different from the Skirty cheat purely because it opens a blank world by default. The Doctor cheat allows the user to switch worlds, pick up creatures and scroll all around Albia. In Doctor mode, Creatures does NOT autosave. Use with caution, with either Gordnorn and Rhodent's BoBCoB tool or Alexander Laemmle's BORG utility.
The cheat can also be applied manually, by using regedit to change the registry key "Privileges" in HKEY_USERS/.Default/Software/Millenium Interactive/Creatures/1.0 from "user" to "doctor".
In The Albian Years version, in Windows Vista and above, the registry entry can be found in HKEY_CURRENT_USER/Software/Gameware Development/Creatures/1.0, and edited as in other versions.