The provided "System.cfg" removes HDR glitches and enables all necessary effects to fully enjoy the Natural Mod. However, low-end systems may encounter performance drop with these settings, because it activates certain very high effects.
If the framerate of the game is too low, open the "System.cfg" with the Windows Notepad and follow the instruction of the last section "Framerate Optimizations".
If you launch a level by using an old savegame, the position of the moon will be the default one (unrealistic). To avoid this, begin a new game or use the provided savegames in "Start menuProgramsNatural ModSavegames". Furthermore, you can launch the desired level by using the console command "map level_name".