San Andreas Multiplayer (SA-MP) is the continued project of the popular mod Vice City Multiplayer (VC-MP) 0.1d. The difference between the two is that SA-MP has server-side scripting is available to make game modes. Pawn scripting is easily understandable with all the available help on the forums and open source game modes. As you may have noticed, if you're familiar with the GTA modding scene, most of these guys are fore-fathers of modding and to have them is such a great achievement itself.