This qualitative case study aimed to investigate Early Childhood Education (ECE) pre-service teachers' perception of development in their technological, pedagogical, content knowledge (TPACK) after designing educational computer games for young children. Participants included 21 ECE pre-service teachers enrolled in the course Instructional Technology and Material Design. The data were collected through focus group interviews, observations, and journals. The results indicated a perceived improvement in TPACK. Moreover, participants described initial difficulty designing educational computer games since they had limited technological knowledge (TK), design knowledge (DK), or experience designing educational computer games (TPACK). However, during the game design, specific TPACK was disseminated, and participants reported increased abilities in using technology and designing computer games for educational purposes.