Sony Open-Sources A Universal Game Level Editor
Sony has open-sourced "LevelEditor", a level editing application for game levels that can be adapted to work with any game engine and uses a nice WYSIWYG interface.
The Sony LevelEditor is out under an Apache license and is designed to create "robust game levels" that can work with any game engine via its API interfaces. LevelEditor appears to be fairly feature complete and in good shape.
The only downside to the LevelEditor is that it's... currently Windows-only. LevelEditor is written in C# and uses Direct3D. However, if LevelEditor works as good as it looks, hopefully open-source game modding fans will take to porting it to Linux.
This open-source level editor is found on GitHub. It's nice to see Sony Computer Entertainment open-sourcing more code!