Three-dimension will be a characteristic of future user interfaces, although we are just starting to gain an understanding of how users can navigate and share information within a virtual 3D environment. Three-dimensional graphical user interfaces (3D-GUI) raise many issues of design, metaphor and usability. This research is devoted to designing a 3D-GUI as a front-end tool for a file management system, in this case, for Microsoft Windows\c{opyright} Explorer; as well as evaluating the efficiency of a 3D application. The software design was implemented by extending the Half-Life 3D engine. This extension provides a directory traversal and basic file management functions, like cut, copy, paste, delete, and so on. This paper shows the design and implementation of a real-world application that contains an efficient 3D-GUI.