The computer game industry has become the fastest growing field of the entertainment industry. However, only a very small number of computer game products overcome the costs of production and generate earnings. According to traditional marketing wisdom, customers’ preferences must be analyzed correctly to create successful products, and in the gaming industry, such information must be considered during the design process. This research aims to explore key factors of heuristic evaluation for game design. A review of literature pertaining to computer games and HCI was conducted along with an empirical research of a Massively Multi-player Online Role-playing Game (MMORPG). We identified 18 usability issues in MMORPG and presented a recommendation relevant to the issues. Empirical data were applied to a new heuristic evaluation framework. We determined the relationship between key factors and four game categories, such as game interface, game play, game narrative, and game mechanics. Moreover, the results presented 54 key factors for a new heuristic evaluation framework for game design. The conclusion presents key implications of our research in a game design context, particularly related to early design processes. r 2007 Elsevier Ltd. All rights reserved.