"an active diversion requiring physical exertion and competition"
"Sport is a physical activity involving large muscle groups, requiring strategic methods, physical training and mental preparation and whose outcome is determined, within a rules framework, by skill, not chance. Sport occurs in an organized, structured and competitive environment where a winner is declared."
Mouse clicking, typing obscenities when hit with a bad beat, punching the desk, getting a drink during a quick break....
But seriously the ability to handle the physical exertion of a tournament that goes 8hours, lots of mental preparation obviously, if you are taking it seriously.
And more skill than chance. There are winning players. It is clearly a game of skill but of course there is chance involved. Look at Chris Moneymaker