United Airlines launched earlier this year MileagePlus promo called Mile Play trying to get select members to spend and fly more. They have had these promotions every few months and just launch a new one yesterday for September.
There are number of offers that are tailored to each member based on their recent United flying activity. Members are required to purchase certain number of flights in business or economy over certain price point.
You can try your luck registering for this offer here.
United Airlines has run similar offers for years and launched these “Mile Play” promos early this year. Seems that based on the name used that United may try to gamify this offer more.
My account was not eligible for this offer (never has been) because I moved it to outside of North America few years ago.