Battlefield Heroes launched in 2009 as a free-to-play, cartoon version of the Battlefield series, developed by DICE and Easy Studios for browser-based play. Players chose between the Royal Army and the National Army in stylized World War II battles. Its whistled main theme became one of the game's most recognizable elements, heard in menus and trailers throughout its life until the servers closed in 2015. Clips of the music still circulate in nostalgia videos, gaming forums and soundboards where former players use it to instantly reference the short-lived shooter.