This paper depicts the process of developing a prototype for a 3D computer game and the underlying game engine. It includes in depth information about game design basics as well as detail about the implementation of various game engine features. These features include a physics engine, modern rendering techniques and advanced shadow mapping algorithms. The elaboration of a game concept and the resulting game design paper is detailed for the game Assembler Bay, which was developed in the scope of this project. Additionally modern games will be analyzed for requirements and expectations at their technologies. The most important of these features are included in the game Assembler Bay.