A well-tested pattern for building an online game backend uses a relational database, such as MySQL. This database stores game world state and essential persistence data. For basic session-based games, the database holds nothing more complicated than the final results of matches. For large, persistent-world, massively multiplayer online (MMO) games, it may be a hugely complicated set of interrelated tables holding player progression and inventory. The speed of queries in the database layer of your backend directly affects the user's experience of responsiveness in the game client.

https://cloud.google.com/architecture/mobile-game-backend-cloud-sql