: The standard client is required to connect to existing RP servers like Evolve Role Play or Arizona RP . You can find the latest stable version (e.g., 0.3.7-R5) on SA-MP.mp .
To play or host a SAMP RP mod, you need a clean installation of Grand Theft Auto: San Andreas (v1.0 US/EU DVD version).
If your goal is to "download a mod" to start your own server, you are looking for a (often written in PAWN). Popular archived and active RP scripts include:
: A MySQL-based script found on Blast.hk featuring complex inventory systems and group/faction management.
: Another open-source script on GitHub that offers optimized player account loading and unique "knockout" systems.