A blockchain gaming multiverse is a collective gaming reality created by integrating a collection of blockchain assets with multiple games.
In other words, a gaming multiverse is a collaborative gaming project where multiple game developers agree to use the same shared, decentralized database for some (or even all) of their in-game assets. This enables gamers to utilize a multiverse asset in every game that is a part of a specific gaming multiverse (e.g., if a player owns a sword in Game A, they will also own it and can use it in Game B).
Unlike gaming multiverses presented in fiction (e.g., the OASIS in Ready Player One), which are centralized (meaning that all games and assets within the multiverse are controlled by a single entity), a blockchain gaming multiverse is decentralized. In-game assets in a blockchain gaming multiverse are owned by gamers, while individual game developers control only the games they create.
Blockchain technology is the only way to create a “real” gaming multiverse, as a centralized multiverse would, in practice, be a single game made and controlled by a single entity.