This engine runs SpaceMercs and all new games from BTE. It is moddable and comes with content creation tools. It is made in java and runs well.
So, this is the new ui! If you look to the upper left you will see a menu called file, which is where you save the ".entity" files. The center left is a Canvas, which I am working on adding an LWJGL Frame to. On the bottom, you can see the toolbar that lets you choose which modifications to use and to the right you see tabs which let you edit different attributes.