After looking around the room the game is being played in, all the players except one are blindfolded. The sighted player then makes a small adjustement to something in the room. They then instruct the other players to remove their blindfolds. They then have 30 seconds to spot the difference. If a player can identify the changed object they get a point and swap places with the player who could just see. If nobody spots the difference the sighted player gets a point. Everyone is then blindfolded again. The player to get 10 points first is the winner.
Source: From the original site.