Many websites offer free online sports games. Three such websites are AddictingGames.com, ESPN.go.com and AllStarSportsGames.com. Commonly offered games include golf, dirt bikes, football, archery, fishing, basketball, and soccer.
AddictingGames.com has a whole section for sports related games including golf, dirt bike racing, car racing, football, archery, fishing, basketball and many more. You do not need to sign up for an account to play the games, but you can create an account to track your high scores and compete with others.
ESPN offers some great online sports games you can play for free. Again with this site, you are not required to sign up for an account to play the games, such as soccer, basketball and football.
AllStarSportsGames.com has games you can play directly on their website for free without having to sign up for an account. They have tons of sports games to play as well as sports trivia quizzes.