Hello there.
I've been working on a little level editor on and off for a few years and it is slowly becoming usable.
It's called Microbrush (now already part 3) because my main focus, for now, is the bare brushwork
And it has two predecessors from long ago, here.
The editor is fully programmable out of the box without third-party tools, lives on a plugin system, supports multiple worlds at once with 2D and 3D views (at whatever angles, clip planes, etc.), freely configurable 3D grid axes for a skewed or rotated grid, alignment to ellipses instead of normal grid cells, configurable grid bases (to 2, to 10, to 42, etc.), text interfaces for settings like the camera for easy storing and recalling, has the essential tools for quick brush creation manipulation including merging and intersecting, seems to work with scenes of about a million brushes in total (64bit version still on my todo list...), various brush input and output formats, has a rather strong key combination sequence configuration format, three distinct selection sets to work with, and many other things I forgot. And I am still developing it.
If there is a bit of interest in this tech, I can look into outputting a Quake 3-compatible map format rather soon and get the version used for that video out. My goal is not to replace another editor, but to just augment the level editing process a bit. Maybe people can do some things faster with my editor than with others, and then combine the strengths.
I am tweeting about new developments here.
-S
