No download is necessary as you’re streaming the game through the same technology that powers Stadia. AT&T envisions a future where publishers could use the technology to offer limited-time demos of their games. The carrier says you could search for a game and then, if you decide to buy it, your progress from the demo would carry over. Coincidently, that’s functionality Google already offers in Stadia through the platform’s “Click to Play Trials” feature.