Within the field of game studies, much ink has been spilt in the quest to define and classify games based on their genre, that is, to determine in which category they belong based on the type of interaction each game affords. Some games lie clearly within an established genre; for example, it is rather difficult to mistake a racing game for a first-person shooter. Other games, however, can fall outside the boundaries of any particular genre, or lie within the perimeters of several genres at once. Such is the case with music games. While some may argue that a game can be considered to be a music game only if its formal elements, such as theme, mechanics or objectives, centre on music, musicians, music making or another music-related activity, in practice the defining characteristics of a music game are much less clear – or rather, are much broader – than with other genres. Many game publishers, players, scholars and critics classify a game as musical simply because it features a particular genre of music in its soundtrack or musicians make appearances as playable characters, despite the fact that little-to-no musical activity is taking place within the game.