Project Props is a mod which seeks to provide the 3D era GTA San Andreas a little touch of realism by increasing map details by adding objects(props).It's sad that R* couldn't give a high details to these maps because of the technical limitations of consoles of that time, PS/PS2 and ended up leaving empty map in some parts. The purpose of this mod is to simply add objects to give more life to the game , making it realistic & immersed.
