The game was also criticized for not being able to be played on the go, because it requires a dark environment.

A security thread that will glow red when exposed to ultraviolet light in a dark environment.

Night vision is the ability to see in a dark environment.

If left in a dark environment for some time, the violet will fade again.

While sleeping at night we fast and are exposed to a quiet, dark environment.

It is triggered by the brain's disfigured perception of what would or could happen when in a dark environment.

They should also be kept in a cool, dark environment.

One could think of them as being like jelly creatures maybe, awash in a dark environment.

Because it is so difficult to see in this dark environment, their eyes, like those of insectivorous bats, have become very small.

As with all textiles, cool, clean, dry and dark environments are most suitable.