Koschei Complex has areas that are pitch black and require either a flashlight or Night Vison Goggles. This is a guide on all the ways you can obtain the goggles.
Koschei Complex is now accessible via Al Mazrah. Head to one of the hidden entrances around the norther part of the map (these are marked as '?' on the map). Once inside you'll fight your way through tough AI enemies as well as the occasional real player. The central room to this facility is pitch black and requires players to use Flashlights or Night Vision Goggles.
Finding Night Vision Goggles (NVG's from this point on) is fairly simply. They are scattered around Al Mazrah on desk and tables or in loot caches. Another way to quickly get yourself a pair before heading into Koschei Complex is to craft them at a Barter Station.
Barter Station Ingredients:
1 x Aged Wine
2 x Emergency Rations
NVG's will take up a slot within your backpack and need to be toggled on and off accordingly. Do this by opening your bag and clicking toggle. Not all of the Koschei Complex is shrouded in darkness so they don't need to be left on. Personally I'd rather this have been a field upgrade or special equipment like the Gas Mask that can automatically toggle itself on and off but this way adds to the tension.