The aim of this master thesis was the creation of a program, which allows to explore the city of Graz using OpenStreetMap-data. Therefor the basis consisting of geoinformatics and OpenStreetMap will be described. OpenStreetMap grew to a huge project with thousands of registered users in just a few years. On the one hand this means, that the database increases at speed, but on the other hand a total quality control is complicated. There a several ways to use OpenStreetMap. Ready-made Maps can be retrieved from the internet or data can be obtained in different formats as vector data, for example. Python is used as the programming language of choice. Python is very versatile and due to the large number of existing modules such as Pygame or PyGTK, results can be achieved quickly. This also applies to game development, which differs because of the artistic aspect from application programming. However, graphics and sound are not the only differences. Game development also distinguishes due to an immediate interaction between computer and human and because of computer opponents, which should have the best artificial intelligence possible. The concepts of Open Source-Software and free Software became important since. Various licences such as the GNU General Public License or the BSD-license are available to ensure, that the further use of free software will be correct.