The free app, compatible with iPhone, Android and Windows Phone devices, also provides fantasy players with alerts regarding scores, trades and news and other features while allowing them to view and post messages to league message boards. The app underscores mobile's suitability for keeping the experience fresh for fans and for delivery of sports content.

?People are spending more time on mobile across the board, but particularly on NFL Sundays as they monitor the performance of their fantasy teams,? said George Leimer, vice president for product management with ESPN Fantasy. ?We think the lighter design of our app will make the experience simply more pleasant. 

?And as fantasy players become more open to the entirety of the experience being on mobile, it's vitally important that we enable our users to do all of the important fantasy tasks on mobile. We?ve made it easy to join and create leagues on mobile.  We've made it easier to invite friends to your league via mobile.  And we've added a lot of fun, social elements to the product, which helps to keep people engaged as the season goes on.?

ESPN has spent the past few years ramping up its mobile offerings for fans and using the medium to drive user engagement.

Its projects have included updating its March Madness ESPN Bracket Bound app for iPhone and Android devices, establishing its ESPN Alerts SMS program to receive real-time information on game standings and breaking news and launching an ESPN Fantasy Football iPad app.

Last month, fans spent 7.4 billion minutes using ESPN digital properties, a June category record and up 62 percent from a year ago.

Coverage of the 2014 FIFA World Cup, NBA Finals, NBA Draft, U.S. Open, Wimbledon, and MLB?s regular season propelled ESPN in the digital-sports category. Bristol, CT-based ESPN reached 80.7 million unique users across computers, smartphones and tablets, a single-month record, and a 56 percent jump from a year ago. The results highlight the sports fan?s growing appetite for mobile-delivered content, and especially for big events.

Although Fantasy Football has run nearly two decades, the emergence of mobile platforms has enriched the program.

?Fantasy football is a week long activity,? Mr. Leimer said. ?If you're not monitoring the performance of your team, you're planning your roster or you?re consuming content to help you make decisions.  

?It's something that you can do everywhere, and we're seeing usage that confirms that trend, with mobile usage doubling in just the last two years alone. 

?That trend forces us to re-think the way we deliver information, the way we organize the product, the visual design ? everything really.  That's a good thing because it forces us to really get focused on the things that are most important to the user and get really, really good at those things.  And ultimately, it all pays off for our fans.?