The legend of the arcade game Polybius, is that in 1981 at a sleepy unnamed arcade in Portland, an arcade game in a plain cabinet appeared one day. People that played the game described the game as incredibly addictive and described symptoms including amnesia, night terrors and the tendency to lose all desire to play video games. Then, only a month or so after its appearance, it vanished just as suspiciously as it arrived. Though there is no evidence of it ever existing, hundreds, to thousands of gamers have come forward saying they played the game. Here's a documentary about Polybius - The Game That Doesn't Exist, for those who are interested.

Legend has it that in the weeks before the famed Chernobyl Nuclear Meltdown, people that lived around the local nuclear power plant reported seeing a terrifying creature that was a large, dark, headless man with hovering, glowing red eyes. Those who say it say that they had terrible nightmares and received threatening phone calls. This clearly has a very striking resemblance to the Mothman legend of West Virginia and the Jersey Devil of New Jersey. Here's a 6 minute video that covers the entire mystery: https://www.youtube.com/watch?v=6bn1weI5K4U

In September of 1880 in Gallatin, Tennessee a farmer named David Lang People vanished into thin air while walking in his field. Two men riding by in a buggy watched him as they rode past, and just poof, he vanished mid-stride. Supposedly, the grass directly in the area where he vanished would grow stronger than all of the surrounding area. The story circulated for decades but gained mainstream attention after an article was published in Fate magazine in July 1953, purporting to contain an interview with Lang's then-living daughter. Read more at historicmysteries.com

In an area of Southern New Jersey called the Pine Barrens, legend has it a winged and hooved creature described as having a goat-like or kangaroo-like head lives. The Jersey Devil legend starts in 1735 when a mother of 12, Jane Leeds, gave birth to her 13th child who was born normally but almost instantly changed into a creature with hooves, a goat-like head, the wings of a bat, and a forked tail. It started growling and screaming before killing the midwife and crawling up the chimney and flying out in the pines. The Jersey Devil has since been reported in the area for centuries including a spotting by Napoleon olden brother Joseph Bonaparte, who claimed to have seen the creature in Bordentown in 1920, later blaming it for killing his livestock after hearing screams and finding tracks. In 1909 it's reported that the creature attacked a trolley car in Camden, officers fired on the creature to no effect which lead to school shutdowns and a vigilante group to hunt the creature. The Philadelphia Zoo even posted a $10,000 reward for the creature.

In 1923, some visitors arrived at the small Brazilian town of Hoer Verde, which had a population of 600 people, to find that they had all disappeared without a trace. The authorities in a nearby city were contacted, but nothing ever came from the investigation. The only extraordinary thing they found was a school blackboard with the words, “There is no salvation.”

The Babushka Lady is a woman who was present during the assassination of President John F Kennedy in 1963 at Dealey Plaza in Dallas, Texas. She was seen by eyewitnesses holding a camera and can be seen in the Zupruder Film, as well as the films of Oroville Nix, Mark Bell, and Marie Munchmore. There is no known footage that shows her face, and the FBI reportedly does not know her identity. While there was a woman named Beverly Oliver who famously came out in 1970 claiming to be the Babushka Lady, it is not commonly believed to be true. It is believed however, that the footage that the Babushka Lady caught that day could be the key to solving who actually killed JFK.

On March 8, 2014, a flight from Kuala Lumpur Internation Airport headed to Beijing. 38 minutes after takeoff, the crew sent their final message. Minutes later the flight disappeared from ATC radar but was tracked by military radar for another hour. In that time it deviated from its original path. All 227 passengers and 12 crew members disappeared. The search for the lost flight became the most expensive in aviation history. While several pieces of debris that washed ashore in the western Indian Ocean during 2015 and 2016, the three-year search of 46,000 square miles ended in 2017 without success.

As of today (January 14th, 2019) Larry Vance, a former investigator with the Transportation Safety Board of Canada has said that he believes that it's "100% murder-suicide" by either the pilot or co-pilot.

The Mandela Effect, or false memory, is a psychological phenomenon is when a person has a memory of something that didn't actually happen, or remembers it differently from how it happened. Someone believe that it's actually proof of the existence of an alternate universe(s). It's called the “Mandela Effect" because many people believe that Nelson Mandela actually died in prison long before his true death, on December 5th, 2013. Thousands of people truly believe and remember his passing before that day. Similar to Mandela’s death, many people remember the Space Shuttle Challenger exploding long before the January 1986 tragedy. In the case of the Challenger explosion, even people working for NASA swear confusion over the date of the tragedy.

The Roswell stone is a mysterious rock discovered in Roswell, New Mexico on September 4th, 2004. In addition to be abnormally smooth and having unusual magnetic properties (which has lead some to believe it to be a meteorite?), the stone is carved with a mysterious pattern of triangles and crescents. What adds another layer of mystery is that this exact pattern was found in crop circles found in England almost two decades ago.

According to retired Air Force Major turned art dealer, Forrest Fenn, in 2010 he buried treasure in the Rocky Mountains worth millions of dollars. When asked why he did this he said he "just wanted to give people some hope."

Fenn told ABC News that he estimates that nearly 350,000 people have gone searching. The only real clue that Fenn has released is in the form of a poem.