One year ago:
A cauldron bubbles in a dark room while a man ran a finger down the page of a book that was yellowed with age. "Ok so the next ingredient is a piece from a shooting star," the man muttered. He picked up a box and spilled it's contents into the cauldron which almost immediately emitted a green light and a long hiss. "And now the final ingredient, an ordinary coin." He took a penny out of his pocket and tossed it into the cauldron.
The light being emitted from the cauldron began changing colors and a deep voice could be heard saying, "Humans of Earth your lives are about to change. In a few moments coins that will transform you will be scattered around the globe. The coins will be black at first but will turn white once the have been used for the first time. To use one simply place it on the back of your wrist. However once you do you will be transformed for forty eight hours. Once the time has passed the transformation will be reversed and you will be unable to transform for the next twenty four hours. While you are transformed and for two hours after the transformation ends you will be resurrected if you should die. You will not know what you will transform into until after the first use of the coin. Once you use one of the coins it is your's to do with as you wish. You may keep it, trade it, sell it, lend it to someone, or give it to someone. Beware though for you can not steal someone's coin or coins. If you try you will be punished. How you use the coins will be up to you. Now the time has come for the coins to be released." A bright white light erupted from the cauldron blasting a hole through the ceilings and roof of the man's house and sending coins across the globe.
In the year since the coins first appeared people have found that they're not as easy to find as they had first thought. Many only managed to find one but the lucky ones have found more. The most someone was able to find so far is twenty coins. They have found quite a few uses for the coins. Criminals of course used them to commit crimes but the police have formed special squads to combat the threat. There was some concern about taking away the criminals' coins when they were locked up but it was soon discovered that as long as the criminals would get them back after getting out it wasn't considered stealing. Of course the police weren't the only ones that used the coins for work related purposes.
The coins transformed people into basically anything that could be imagined, both living and non-living. As a result new options for sports opened up. For instance there were a few people who had coins that transformed them into cars that could fly so auto racing took on a new twist.
The most common new sport were the transformation tournaments. Each tournament consisted of anywhere from three to six rounds and with each round the players had to use a different coin so you had to have at least three coins in order to enter a tournament. Players gained points for each kill they made depending on the relative strength of the players and how well they avoid getting injured. At the end of the rounds the person with the most points wins.