The potential of non-educational games in learning is well-established, but there have been relatively few empirical studies attempting to explore the design and development of games that are tailored to address educational objectives in a particular domain, for example, in ocean literacy. Ocean literacy can be defined as having an understanding of the marine world and of one’s relationship with it. Simultaneously, there is a recognized correlation between players’ motivation and learning outcomes, yet there is a lack of research investigating the link between gaming motivations and informal learning within games. This study aims to fill the gap by developing and evaluating an ocean literacy themed entertainment game specifically designed for enhancing player’s motivation. The design and evaluation process employed an informal learning framework, incorporating Self-Determination theory, Constructivism, and the Gaming Involvement and Informal Learning framework. Two playtests were conducted, combined with online survey and semi-structured interviews, in order to investigate game design factors that may affect motivations, players’ informal learning behavior, and their views on the playtest game. The playtesters in the research were college students. This study provides support that there exists a notable positive correlation between players’ motivation to play and their informal learning behavior. Additionally, an important outcome of this research is that the incorporation of a certain degree of autonomy and goal rewards in game goal setting can enhance players’ motivation to play. After a series of investigations and interviews, it can be concluded that gameplay has the potential to facilitate efficacious comprehension of information and expeditious knowledge acquisition. This highlights the potential of games as an avenue for simultaneous play and learning, underscoring their importance not only as sources of entertainment but also as a means of knowledge acquisition.