I would guess that killing is not very sporting for the person being killed, unless the person is killed in a game of darts, which is clearly a sport.
"Killer" is a 'knock-out' game for two or more players (at its best at 4-6 players). Initially each player throws a dart at the board with their non-dominant hand to obtain their 'number'. No two players can have the same number. Once everyone has a number, each player takes it in turn to get their number five times with their three darts (doubles count twice, and triples three times). Once a person has reached 5, they become a 'killer'. This means they can aim for other peoples numbers, taking a point off for each time they hit (doubles x2, triples x3). If a person gets to zero they are out. A killer can aim for anyone's numbers, even another killer's. You cannot get more than 5 points. The winner is 'the last man standing'