You and your friends can participate in private and exclusive contests together by creating and joining your own league. You can choose between 10 sports, including NFL, in which to compete with one another. You can view the league leaderboards to track your performance.
You can play for as long as you want with as many friends as you want.
If you want another player to become a member of your league, you can send them an invitation via text, email, or posting on Facebook/Twitter.
Create your own league here.
Note: The max number of entries for a private league is 200.