Before you can use pystk you need to setup the OpenGL rendering engine and graphics settings.
There are three default settings GraphicsConfig::ld (lowest), GraphicsConfig::sd (medium), GraphicsConfig::hd (high).
Depending on your graphics hardware each setting might perform slightly differently (ld fastest, hd slowest).
To setup pystk call:
pystk.init(pystk.GraphicsConfig.hd())
# Only call init once per process
... # use pystk
pystk.clean() # Optional, will be called atexit
# Do not call pystk after clean