These scripts retrieve data from Natural Earth's website and computes a the data/countries.geojson file.
The preparation process work under Linux and Windows (under a git bash session).
The scripts makes use of the wonderful ogr2ogr tool (part of the gdal suite) and a few other shell commands that are glued together with tuttle, a make for data. Therefore, you'll need to install git, gdal and tuttle.
Make sure the ogr2ogr tool is available on command line.
After you have checked out the code, go into the script directory and run the processing :
cd scripts
tuttle run