The "Top Paid" category isn't really the whole story, since there's no official "free demo" system in the app store. Instead, games are set up as a "free + microtransactions" and then the only in app purchase is "buy the whole game." But unless you look closely down at the bottom of the store page, you can't distinguish games like this from the microtransaction trash.

PinOut comes to mind as an example, I'm sure there are many others: https://apps.apple.com/us/app/pinout/id1108417718

  In-App Purchases
  PinOut Premium $2.99