Game publishers are finding it increasingly difficult to make money on free-to-play games despite an expanding universe of players, Dean Takahashi writes. "The shelf space is infinite. But it is really hard to monetize," former Digital Chocolate executive Trip Hawkins says. The most successful gaming companies are throwing marketing dollars toward discovery, meaning the richer they are, the more gamers they can acquire. Some companies, such as Rovio, are profiting from game-related licensing. Others, such as NativeX, are considering native advertising of relevant content to gamers, Takahashi writes.