This means that now the plugin can be easily installed from the QGIS plugin manager. Just remember to enable “Show also experimental plugins” under plugins->Manage and Install->Settings. See also the README.
The mappy plugin has been designed to provide simplified methods for generating polygonal layers starting from contacts and points, making it possible to overcome the annoying issue of directly editing polygons when producing geological (or any polygon-based) maps.
Mappy is also described on this 2020 EPSC abstract.