If chosen carefully according to teaching purposes and incorporated into the curriculum, games can enhance teaching and learning. The use of didactic games while teaching maths can support students' motivation and performance during the lesson. Therefore, educational games should be preferred in maths classes as an alternative teaching method. In this study, math teacher candidates' processes of developing educational games were observed, and the aim was to determine their opinions about the process. 52 teacher candidates form the participants of this research, which was conducted as a case study. Teacher candidates were informed about the properties of educational games, and they were asked to develop a mathematical game according to the Game Design Key Model developed by Özkan (2018). The research data was obtained using Game Design Key Model, structured interview forms, and daily plans. The obtained data was analyzed with descriptive and content analysis techniques. The games developed for the study were categorized according to their grade level, design purpose, learning area, game type, the way the game was developed, goal, the obstacle of the game, basic mechanics, feedback, and the number of players. Teacher candidates' views on the process were categorized as factors that make the process difficult and easier, and things that are enjoyed and disliked during the process.