Nighttime fears are a type of childhood fear, which, under normal circumstances, reduce as children grow older. However, in instances where nighttime fears persist, there may be negative physical and psychological effects on the child. In addition to serving as an entertainment medium, researchers have used digital games as a method for training children to handle and alleviate their fears. This study aimed to investigate nighttime fears among children in Taiwan and to use the collected data to design a conceptual digital game for mobile devices that may assist children to face and alleviate their nighttime fears. A focus group with seven parents was organized to collect data on children's nighttime fears. The Koala Fear Questionnaire (KFQ) was subsequently used as a survey instrument, conducted among 35 children, aged between 7 and 10 years old. Finally, a conceptual digital game design was proposed based on the analysis results of the focus group and survey.