in english.txt

STR_CONFIG_SETTING_SLOW_TIME_FACTOR	                            :{LTBLUE}Slow time factor: {ORANGE}{STRING2}
STR_CONFIG_SETTING_SLOW_TIME_FACTOR_HELPTEXT                    :Slow down the time in game. Default 1 is normal speed. Higher values make time in game run slower.

settings_type.h
uint16   slow_time_factor;				 ///< How fast the time passes. Higher values the slower it pass. Default 1 normal speed
at the struct GameCreationSettings

settings_gui.cpp

environment->Add(new SettingEntry("game_creation.slow_time_factor"));

settings.ini
[SDT_VAR]
base     = GameSettings
var	= game_creation.slow_time_factor
type     = SLE_UINT16
from     = 200
def      = 1
min      = 1
max      = 365
interval = 1
str      = STR_CONFIG_SETTING_SLOW_TIME_FACTOR
strval   = STR_JUST_INT
cat      = SC_BASIC