It appears to be ad supported with an in-app purchase to disable ads for $1.99. According to eurogamer, "You can play them forever without paying, or you can

It appears to be ad supported with an in-app purchase to disable ads for $1.99. According to eurogamer, "You can play them forever without paying, or you can spend a one-off fee of £1.99 to ditch the ads, which appear on the start screen, the save screen, and I think at launch, but will not interrupt play in anyway" http://www.eurogamer.net/articles/2017-06-21-segas-back-catalogue-is-headed-to-mobile-with-sega-forever http://www.eurogamer.net/articles/2017-06-21-segas-back-cata...