What is OpenCity ?
OpenCity is a full 3D city simulator game project. It is written in standard C++ with OpenGL and SDL from scratch. It is not intended to be a clone of any famous city simulator from Max*s. So, if you are looking to download a free SimCity 4 like, please forget OpenCity.
OpenCity is also an OpenGL/SDL/C++ game programming tutorial. In the resources section, you can find the micro simulators' algorithm, design document, UML diagram and information about other issues. The UML diagram is edited with Umbrello, the free UML diagram editor for KDE.
Not quite sure that Opencity is what we would call a skill game or not however it has been included because it is a 3D simulation game. OpenCity is a full 3D city simulator game project.