Wikipedia wrote:Dark Forces was commonly called a Doom clone, but the game makes significant expansion upon the gameplay features present in Doom.[4] The new gameplay mechanisms that were not common at the time of release include the ability to look in all directions, duck, jump, run and swim.[5] The usage of multiple floor levels is another technical advance in the first-person shooter genre.[8] To produce these new features, the developers wrote a game engine from scratch.[9] The Jedi engine can create gameplay and graphical elements such as fully 3D objects, atmospheric effects such as fog and haze, animated textures and shading.