In the game graphic design process, design results are based on ideas that drives major decisions. Many information and stimuli could help to determine an initial game graphic design concept which is called concept generation. In this study Related Search Term and WordNet stimuli were given to the game design students in the concept generation. This study seeks to clarify which kind of stimuli contributes more to the creativity of the game graphic design concept. As a result, significant difference was found in creativity scores between two conditions. This result showed that related search terms which are based on collective knowledge could assist as stimuli on concept generation more effectively than WordNet which offers semantic dictionary definitions.