Video games borrow fictional worlds from other media or create their own unique worlds to spread to a wider audience but how these virtual worlds are created or what kind of components are used to build them are important questions that can be studied well with a systematic analysis of their content. It is also important to note here that once a fictional world is successful for one type of media, it usually expands through different media, which is defined as media narrative convergence or transmedia storytelling. This study attempts to find out the patterns and trends of worldbuilding methods in the fictional worlds of computer role-playing games. Adopting a systematic content analysis approach, 10 most successful computer roleplaying games are analyzed to identify their worldbuilding components and transmedial extensions. The analysis of video games includes information about the game world (world type, world map, distinct elements), points of interest and their corresponding map icons, species found in the fictional world (player species, flora, fungi, creatures, sentient species), information about culture (religion, language, government type, social organizations, the use of magic or technology). In this regard, repeating patterns of worldbuilding in games are presented and the framework that consists of three components (place, species, culture). The effects of each fictional world on different media are also given.