Almost all of the area design of Blitz and Massive took place in 3d Studio, creating points to define where objects would be, etc…
After the game went on hold, we decided we needed a better tool for this, and so we created the Genesis Editor, which was supposed to be a “one-stop” design tool, with deep integration with Spellbook (the viewport, for example, was full Spellbook).
It allowed for the normal editor operations, but also some atypical ones like importing shape files from AutoCAD to generate cities from real data (for the GIS projects), a façade editor for the buildings and a plethora of small tools to help us in designing rich areas in a simple way.
It was built on C++ with wxWidgets as the UI framework, and I was responsible for most of the design, the Spellbook system and some of the object/component model.
This was later replaced by the Surge Editor, which had a tigher coupling with the engine and the game logic.