PubNub BLOCKS extends PubNub's functionality to allow executing functions on streaming data, which is well-suited for turn-based multiplayer games on web and mobile platforms. The tutorial guides users through creating a simple multiplayer Hangman game using Swift for the UI and PubNub's Hangman BLOCK to handle the game's logic. Users must set up a Swift application with multiple view controllers to manage different aspects of the game, such as setting the GameID, choosing the word, and playing the game. The tutorial explains how to configure the Hangman BLOCK to handle inputs and track game status, updating the app's UI with real-time feedback from the BLOCK, and enabling multiple players to join the same game by entering a shared GameID. The BLOCKS catalog offers various pre-designed modules, encouraging developers to explore and customize BLOCKS for their applications.