To most people rock-paper-scissors is a harmless bit of fun, like flipping a coin or drawing straws. Something they play, perhaps, when deciding who should carry out a trivial task. Douglas Walker takes it a little more seriously. He once played with his wife to decide which house to buy. He threw rock, she threw paper - so he had to buy the more expensive home she wanted. 'I employ the game as a tool to make casual decisions like who takes the dog out for a walk or who changes the kids' diapers. My family totally loves it,' says Walker, chairman of the World Rock Paper Scissors Society. 'My father used it to resolve disputes in his last will and testament.' He is in town to promote the World RPS Championship Asia League, the first time such a competition has been held in Hong Kong. He expects more than 500 players to take part, with the winner getting a free ticket to Toronto to compete in the world championships next month. Lee Rammage, world champion in 2004, is also here to take on professors and mathematics students. But he met his match yesterday, beaten by Phoebe Lam Yui-sze, a Primary Five pupil who just won the gold award in the International Mathematics Competition in Singapore. 'Kids are hardest to beat because they generally don't have any idea what they are going to throw next,' Rammage said. His tactics? Observe your opponents before the match to understand their 'chaotic pattern'. 'But in competitions people go to great lengths to distract me.' It is not unusual for women to cause a distraction by wearing bikinis, he said. Many see the game as one of luck, but the two masters disagree. Walker says the more experienced a player, the less luck is involved. Patterns are discernible. Dr Cheng Lee-ming, vice-president of the Mathematics Education Promotion Association, said it was also a mind game. He said males throw rock 37 per cent of the time, a reflection of their aggressiveness, while women throw scissors 37 per cent of the time - which he says reflects their more devious nature. The competition begins on October 18 in Sha Tin New Town Plaza. Players can apply until October 16 for the family and children division, and October 22 for the open division, for those aged 19 and above. Entry is free.