Explore the critical role of game testing in this 16-minute lecture from the Association for Computing Machinery (ACM). Delve into the principles of games user research, learn effective methods for observing and questioning players, and discover strategies for designing impactful testing protocols. Understand how to evaluate games by assessing player motivations, behaviors, and reactions to gameplay. Examine various evaluation designs that support rapid iteration, compare alternative designs, and measure usability. Gain insights into the importance of testing in creating successful games and learn how entire research disciplines have emerged to support this crucial aspect of game development.