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: Users can download a base app for free but must pay to unlock premium features, such as advanced filters in a photo editor or additional levels in a game.

: Aspiring writers can buy or download guides and "fact sheets" that teach how to structure a feature article —a long-form narrative piece that goes beyond basic facts to tell a compelling story. buy download

: Participants are given a fixed amount of "play money" and a list of potential features, each with a "price" based on its development complexity. : Users can download a base app for