Duke Nukem Forever is part four in a series of PC games featuring Duke Nukem as the hero. Parts one (Duke Nukem) and two (Duke Nukem 2) were sidescrollers/platform games, and part three, Duke Nukem 3D, was an FPS. Duke Nukem 3D became one of the top-selling games of all time, and is a very important part of FPS gaming history; it is one of the few "legendary" titles, together with Quake and Doom. The game is one of the most sophisticated FPS games ever. It features everything the Unreal engine has, but also features things like LOD, skeletal animation, and motion capture, for an optimal playing experience.