Free-to-play games are rarely free. They usually include microtransactions and in-app purchases that can sneakily add up over time. The Federal Trade Commission has settled with Apple, concluding that the company violated the FTC Act with how it enabled much-too-easy access to microtransactions within iOS.
Specifically, the complaint points out the ability to make an unlimited number of transactions in a 15 minute window after entering an Apple ID password. The company currently does not prompt users of this time period when making an initial purchase.
The FTC specifically pointed out (via Joystiq) that the commission has received "at least tens of thousands of complaints" regarding unauthorized in-app purchases, with some customers having thousands of dollars of unauthorized purchases from their children.
Full refunds, totaling a minimum of $32.5 million, will go to affected customers as a result of the settlement. In addition, Apple will have to modify its billing practices "to ensure that Apple obtains consumers' express, informed consent prior to billing them for in-app charges, and that if the company gets consumers' consent for future charges, consumers must have the option to withdraw their consent at any time." These changes must go into effect by the end of March.