... of stages '.mki3d' files
'tokens' - token shapes '.mki3d' files
Just place the files with your designs in the respective sub-directories of the main assets directory. Shapes are selected randomly from each sub-directory for each stage.
The AppImage file 'mki3dgame-x86_64.AppImage' needs to be set executable on Linux systems. ( See instructions on http://appimage.org/ how to download and execute such files.)