Video game music is the soundtrack or background music accompanying video games. Originally limited to simple melodies by early sound synthesizer technology, video game music has grown to include the same breadth and complexity associated with television and movie soundtracks. While simple synthesizer pieces are still common, game music now can include full orchestral pieces and licensed popular music. Video games can now also generate or alter their soundtrack based on the player's current actions or situation, such as indicating missed actions in rhythm games.Beginning in the early 2000s, it became increasingly common for video game soundtracks to be commercially sold or performed in concerts that focus on video game music. The early limitations on video game music also inspired the style of music known as chiptunes that use the original simple melodic styles, sometimes sampled directly from classic games, with more complex patterns or mixed with the traditional music styles.With the expansion of the video game market, artists going between popular music, classical music, the film industry and video games has become more common. Composers and artists famous for other music—such as film composers Harry Gregson-Williams, Trent Reznor and Hans Zimmer—have worked on soundtracks for recent games, while Michael Giacchino, now normally known for his film scores, began with Mickey Mania and continued with the Medal of Honor series.