In the world I am currently writing there was an event known as the Darkening. Imagine if you will one day you go to sleep and then you wake up seemingly years or so later with no real recollection of anything that took place during that time and now you are with out the ability to see. Your senses of hearing, smell, touch, and taste are greatly improved yes. But you can't see. That is what the Darkening is, the loss of humanities sight and the years that followed. Many cultures of the Darkened (What humanity now calls themselves) have different explanations of what happened in the times of the darkening. A few common threads do exist though.

The first being that some strange beings had come to Earth some even remember what they looked like, though most remember what they sounded like, smelt like, and felt like. But its never clear, almost like a dream of sorts. The best way these being were described by those who actually seen them were large squid like beings with purple or pink skin. The more common descriptions are like this. Smooth wrinkled skin like a half rotted peach, smelled like seafood or like an ocean, sounded like a drowning creature if they ever spoke to you but had a piecing voice of terror if they spoke to you un your head.

The second common thread is that there must have been some great battle... The world feels a lot more ruined then it would be normally, and even nature has started its slow reclamation of the cities, some even remember being in a fight of sorts or at least being present in one, near one, or some remember beating somethings head in or stabbing something but they can't ever remember what it was.

What none of these Darkened know or more accurately remember is that on 2011 the Ilrasi a squid like race of beings with interdimensional capabilities had come to earth seeking new hosts for their children, more or less they are like the Illithid from DND but more scary. The Ilrasi had made a small error in the reading of human minds, they had though humanity needed to be blinded to unlock their psionic potential so that the next generation of Ilrasi could be had. After confirming this with a few experiments the Ilrasi had unleashed an undetecible gas into the atmosphere that when ever it rained would get to humans. Over the course of a few weeks humanity went blind, then had their eyes slowly be reabsorbed into their body, their other senses improved along with them growing in accordance. When the Ilrasi had made themselves known instead of being met by a docile slave live stock they could use, they were met with functionally psychically deaf masses who were very angry and scared that they could no longer see. After almost 18 years of war and loose skirmishes, the Ilrasi cut their losses, and left behind a psychic bomb of sorts that would numb and reset the minds of Humans across the globe for years to come. So in truth, if you were say 6 or so when you fell asleep the night the Ilrasi arrived, you would be almost 36 when you "woke" back up... You may have a family, may be a parent and a member of a tribe you have very little cognitive memory of but somehow you instinctually know everyone in it, and you have a small amount of memory of them. This later event is known as the waking but very few people would have called it as such, most don't have a name for it at all.
If anyone has any questions about this world ask me and I will do my best to answer but this was one of the events that shaped the world. And I thought It'd be cool to share.