A Unknown is someone with the ability to use power. Its unclear why theres a fight but most fights starts with Dark unknown. There appears to be no rules at the current moment and the only one who knows anything is Noui and Ie. The story of unknown first started at blogger then moved into Visual Novel Game since then the whole story is now a Visual Novel with many different events. Its unclear how these powers are activated but it has lean to the emotion and thought. Anyone can be a Unknown as told in 'The Unknowns saga', a ghost, a wild person, normal person, elf, etc.
In a cutscene, Noui told that the Unknowns were fighting since they were born. There is a possible link that many of the Unknowns have been reborn. Many believe that Unknown means a pokemon named "Unknown" which is not true. Most Unknowns have a backstory before entering the 'Unknowns Saga series', a demo game called 'The Unknowns chronicles' shows current Unknowns back stories but not releasing new information on a Unknown. Noui believes that Angels power is too great and never tries to give him a lot of info, as in Dark unknown who always wants to kill Unknown #1 so he can rule the world. Monsters have appear to reclaim earth as they were falsely seal away for years, every so often they come back.
They are consider to be the strongest among all others, Unknown #0 is the most feared as it could bring destruction to all. Light Unknowns are able to use other powers outside their current power but at the same time they can't go beyond that limit. Dark Unknowns hate Light Unknowns, none of them can agree on one thing without fighting.
They are consider to be the most annoying among any other, time and time again they appear where no one wants them to show up. True to their name none of them have the same powers or even related powers. They trick every other Unknowns either by accident for intentional, 80% of all Unique Unknowns have powers that can control the user body. 20% are tricks that make user do a current action without any real powers done by them.
They are considered to be the laziest Unknowns ever, all their powers are useless without the help of #200. Even though there powers are not great, they do have an advantage over all others, they can build whatever machine or alchemy works. Unlike magic that everyone else use, Tech Unknowns attacks are real damage.
They are considered the most wanted Unknowns, every Dark Unknown has the ability to break laws within reason. Together they can bring down any Unknown except zero, which in rare cases never happens to find him/her. Dark Unknowns are notorious for causing war, fights, breaking the 4th wall, ruining everything they hate. Most of them come from bad living conditions and many believed they could use there powers for good if they were treated right