I was wondering if possible to retrieve and change World properties in-game, especially the horizon_color.
I'm not sure if this is what you want:
import bge scene = bge.logic.getCurrentScene() # background saveit = scene.world.backgroundColor scene.world.backgroundColor = [r,g,b] # ambient light scene.world.ambientColor = [r,g,b]
r,g,b float values from 0 to 1.
If you have mist enabled, you should also do:
# mist color scene.world.mistColor = [r,g,b]