It's all made from scratch. Only used the First Person Template for the player character itself, but everything else is made by me. To make the map dark, all you need to do is lower the sun downwards, build the lighting and the map should now be nighttime (dark). There's some tutorials on Youtube that I followed on how to make dark maps for horror games n such. You can follow those if you're trying to make some horror games in Unreal Engine 4.