C3/DS Map Editor
From Creatures Wikia
The C3/DS Map Editor is a Windows program developed by Creature Labs that allows you to graphically create new metarooms or alter existing ones. It was originally used internally, then sold through CDN and now is available for free.
The program allows you to generate CAOS and retrieve the map data from the game. A minor issue is that it displays low-quality versions of the backgrounds from generated bitmap files, instead of using the game backgrounds.