This is the original level editor created by Id Software to create the levels for Doom. In developing Doom, Id used NeXTStep workstations, which at the time were considered very advanced. There is some information about the development process, including screenshots, on Gamasutra.
The goal of this project is to port the DoomEd source code to Mac OS X, which is derived from NeXTStep and still has similar Objective C-based APIs. There is a secondary goal to get it running on other operating systems using other implementations of the OpenStep API, such as GNUstep and Cocotron.