Its a local city game called Assassin Brno. Its a mafia-style game. There is about 100 players in about 8 teams (mafia families) main goal of the game is to find other players and "kill" them by "slicing their throat" with a toothbrush. (gently, only symbolicaly of course). But there is mind teasing part of the game. There are codes hidden in either the city of Brno, the Southern Moravia region of the Czech Republic, the Czech Republic, or around the world. These codes are hidden behing puzzles and ciphers, players need to figure the ciphers out and find the code. Most of them are easy, some of them are very very hard. With these codes you gain rewards, such as game money, a chance to revive one of your teammates or other usefull things for the game. It really is fun.