Create an Interactive Scavenger Hunt with Nexmo SMS and Voice API

The author proposes creating an interactive scavenger hunt app using Nexmo's Voice and SMS APIs, Express, and Node.js. To start, users need to create a Vonage account, purchase a Nexmo phone number, and set up a Nexmo voice application. They then link their phone number to the application, generating QR codes that lead to a Glitch project. The app allows users to record clues, which are stored in an asset file on Glitch. When a user scans a clue with their smartphone, the app sends an SMS to the designated Nexmo number, and upon receiving the message, the phone makes a call to play the next clue's audio recording. The game continues until all clues have been found, providing a fun and engaging way for users to explore their city or neighborhood.