In the past few years, the open-source desktop planetarium Stellarium has become a favorite application for researchers in the fields of archaeo- and ethnoastronomy. While exchangeable sky cultures had been a unique feature of this program already a decade ago, the author has joined the development team several years ago and started a long-time commitment to increase the astronomical accuracy and applicability of Stellarium towards 3-D visualization of architecture embedded in its surrounding landscape. An accurately created and properly oriented landscape model, in the best case based on a LIDAR terrain model with terrestrial laser scan or image-based model, can now be loaded under the artificial sky of this program. This approach allows for research of many phenomena like orientation or shadow studies of monumental architecture which else would require extended or frequent on-site visits or would be entirely impossible due to changes in the sky by orientation changes of Earths axis or stellar proper motion. In addition, the high quality of visual simulation immediately allows the creation of images targeted to a wider audience. The latest development combines Stellarium with a game engine, the basic toolkit for the creation of 3-D computer games. This combination allows the creation of textquotedblSerious Games, like a simulation and demonstration of the use of historical astronomical instruments.