With darkness being a factor it would be neat to it actually affecting how the game looks, by default all places that are closed away from the player should be darker, more dim colored to represent the player's vision, think of it as a very weak pseudo-rogue vision effect, also serving as a way to know if you are in someones sight, when its dark this area becomes smaller, your vision also gets less useful at night making things look blurrier the further away they are unless they are close to a light source.
Lanterns can be used to see the area around you better but make you extremely easy to see.
Flashlights can be aimed to see a long cone around you but while they increase your detectability people will only know you sre there and will take a bit to recognise you.
Nightvision Goggles show you mostly everything but on a green tint, it raises detectability sligthy, removes the ability to hiden in plain sight and makes you sligthy more noise.
This equipement is also used by patrolling cops and goons, other fuctions such as blinding lights and scaring animals away could work for further festures.