GTA: Underground is a mod which focusses on combining the maps from Rockstar's 3D universe. This means the GTA: Vice City, GTA: III, Manhunt, Manhunt II, and Bully maps will be implemented. Not only that, but it tries to implement all of the features these games offered aswell, in the same style as the original GTA: San Andreas content. This includes the vehicles, weapons, pedestrians, scripted features, interiors, shops, safehouses, weather, and much more.