What does it do?

Night Vision Shaders makes the game brighter, so you see well in caves, in the nether, underwater, etc.

How do I activate it?

You can simply enable it as resourcepack (Copy the .zip into the resourcepack directory). If you are using Sodium or Iris, the Sodium Core Shader Support mod is required.

How is it different from other brightness packs?

While making the game brighter it also keeps the game aesthetic:

• fog is not completely removed, it just starts further away
• light sources still emit light
• blocks still cast shadow, but less dark
• it works with Sodium (requires Sodium Core Shader Support mod)

Does it work with Optifine?

No.