It's currently only on mac app store but I have demo versions for mac and windows here: https://drive.google.com/drive/folders/1jhpub6pfIS0tvbFzoiBq...

The website is here http://www.ludigraphix.org/ but the documentation is still a little short.

The main difference with other drawing tools is that shapes are defined by points that can be shared between shapes. It can be seen as a sort of simplified crossover of Inkscape and Geogebra.