The Blue Whale killer challenge was developed by a Russian psychology student, Philipp Budeikin. He was expelled from his university and said in a statement that he invented the game to 'clean' the society of people who are of no value.
Another 17-year old Russian girl has been detained recently as she is accused of being the 'mastermind' behind the game. Earlier a participant herself, she is known to be responsible for introducing the 50 challenges which instruct the players to self-harm. The killer online game originated in Russia and has now spread to other parts of the world. It is not freely available and is not a downloadable game, app or software. It is shared among very secretive groups on social media networks. Many reports suggest that you don't choose to play Blue Whale, the creators seek you out and send you an invitation to join.
An online administrator gives the player challenges over a period of 50 days. After completion of every task, the player is expected to share photo as proof for approval. The first few challenges are easy but the subsequent ones turn sinister, challenging you to hurt yourself. They are meant to condition you to ultimately commit suicide. The tasks are 'adaptable' and are tweaked by the curator as per the geographical location of the player.
Although there is no clear set of 50 challenges, given below is the list of the likely tasks that are given to the participant. These were shared by someone on Reddit. As said earlier, the task may vary for participants depending on the player's geographical location. It could even change according to the player's age and sex. To be honest, it could even depend on the whims of the administrator.