 The prototype used Nvidia PhysX and an Apex physics engine with ragdoll physics for the goat and human models within the Unreal Engine 3 , a game engine they were familiar with from the Sanctum series . In @-@ game assets were purchased from third @-@ party vendors instead of developed in @-@ house , such as the original goat model which the studio acquired for use for less than $ 20 . The prototype was meant to be a parody of various other " weirdly successful " Simulation games presently available , such as Euro Truck Simulator . Ibrisagic had no intention of this becoming a full title , instead only offering the prototype for him and other developers to learn the Unreal Engine alongside other developers that were developing prototypes in more earnest . 
