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. I work on it at my spare time, and I really meant it "my spare time" !
There has been no work on this game for quite some time or it was left in an unfinished state and there is no support by the developer or anyone else.