When Wolfire attempted to sell its own games at a lower cost off of Steam’s platform, Valve told them that they would lose access to the Steam market, effectively telling them that independent developers on Steam are not allowed to offer lower prices elsewhere. But losing access to the core audience on Steam would effectively mean losing the business, and thus Valve is able to use its market power to dictate how games are sold, and at what price. This is a classic monopoly problem that the Open App Markets Act addresses.