As hoped, it’s been confirmed that Stadia will support game trials. It’s not clear if all games will be available as trials, but for those that are you’ll be able to play for a fixed amount of time for no charge before you’re forced to purchase the game.
Given that many of the Stadia games will be new to players, this feature should help give early adopters more games to play with, and hopefully help developers sell more copies of their games.
You can learn more about this in the Stadiacast interview with John Justice (VP, Head of Product at Stadia) from a few days ago.