Sure, Cosmoform is an editor I wrote from scratch using C#/WPF/C++. I started working on it since 2007... the goal was to have an editor that allows me to build a wide variety of games, not just limited to 3D FPS games or RTS games or whatever (e.g. as is the case with Unreal or Frostbite).
I have dealt with a variety of real-world editors during my days at EA, and I wanted to have something that saves me from all the sufferings I had to go through when using their editors (Frostbite 2+ being an exception.. that one is really slick). Mainly, bad inconsistent interface design.. where under every button lies a crash or an exception.
So, kinda out of frustration, I started this rather too-large-for-one-person project: a full game editor that can serve all disciplines in game development. For example, a programmer does certain tasks while a level designer does something else that is also different to an artist. Hence, I made Cosmoform with the concept of "Role" or "Discipline" which you specify when you are working (see pic below).
Each role exposes different controls to the user. For example, the "Programmer" mode can define data structures and dictate the build process and specify how assets make it into the game run-time and how the data is stored...etc. Such controls are not exposed to "Designer" or "Art" mode in order to avoid cluttering the UI with unnecessary buttons and menus.
Once everything in place, you can press one button to build the entire game and get a ready-to-burn .ISO or .MSI installer for your game which you can distribute to your clients. The picture below is for the "Disc Layout" editor, through which you specify the CD contents and their layout (order of files on the disc, inside to outside).
6 years from starting developing Cosmoform, I still feel I need to do a lot of work, as there are many features that have not been implemented yet and are waiting in the design documents, but at least it is stable and productive. Moreover, it's starting to look a bit out-dated and I'm considering upgrading its UI controls with something more sophisticated than plain .NET controls.
I hope you like this story