Although 2020 saw the closure of many economies due to the COVID-19, but the digital games and video industry saw growth and recovery.
The Exchange WorldWide report mentioned that more than 75% of online players want to replace their virtual assets in a currency that can be used through multiple platforms.

read the report from here: https://dailygazette.com/is-cryptocurrency-the-future-of-online-gaming/

In-app purchases can be done by using cryptocurrency or selling game elements and converted for bitcoin.

your duplication lies in preparing an attractive game and then the possibility of drag using encrypted currencies or buy some things using it and then you can win the ads and sell some stuff inside the game.
you can earn from making NFT games.

read more https://www.financialexpress.com/money/how-crypto-gaming-gamefi-is-emerging-as-the-new-way-to-make-money/2326958/