The role of driver is changing from controller to regulator as automated vehicles become more common. This change leads to deceased situation awareness (SA) because of passive engagement and increased non-driving related tasks (NDRT), and might affected drivers' takeover. This study designed a gamified prototype named Dangerous Slime to help drivers maintain SA during automated driving. Dangerous Slime turned surrounding cars into slimes that attacked drivers' cars; drivers need to response to these attacks, which increased their attention to nearby objects. Drivers can take the game as non-driving related tasks (NDRTs) during the whole automated driving process. When compared to NDRT of watching films, the game achieved an improvement in drivers' SA and positive user feedback. Moreover, the styles of games affect drivers' behavior and SA. This study revealed how the game influenced drivers' SA, and took a step toward improving the safety of automated driving in a pleasant way.