Gravity Bone is a freeware first-person adventure video game developed by Blendo Games, and released on August 28, 2008. The game employs a modified version of id Software's id Tech 2 engine—originally used for Quake 2—and incorporates music from films by director Wong Kar-wai, which were originally performed by Xavier Cugat. Four incarnations of the game were produced during its one-year development; the first featured more common first-person shooter elements than the released version. Subsequent versions shifted in a new direction, with the inclusion of more spy-oriented gameplay.