It's a Moondust development tool intended for game creators. It allows the user to define a hit (collision) box for each respective frame of a playable character, and also allows developers to calibrate any incorrect positions of the frames in an SMBX64 playable character sprite.
More information on the Moondust Wiki...
- CMakeLists.txt - project file for CMake
- version.h - Version information
- _resources - Hardcoded editor resources