Where they differ, however, is in approach. They turn San Andreas into a persistent online multiplayer world that allows players to embark on the full gamut of GTA-like activities - killing sprees, racing, stunts, heists, running away from the police, and so on. SA-MP and MTA are both very similar to GTA Online at first glance. (To put a number on it, SteamSpy estimates over 1.2 million GTA 5 players in the past two weeks, with peak concurrent players consistently around 50,000.) Even the massively-popular GTA 5, replete with a sprawling online mode of its own that consistently puts it in Steam's top 10 games by player count, fares no better than its ancestor. They put many of the biggest current PC games to shame.
These certainly aren't numbers to be sneezed at. I went to talk to members of both mod communities to find out what keeps them playing. Its two most popular online multiplayer mods currently have a million or more active players between them - one, Multi Theft Auto, had 616,000 players in July (up from just 33k in February 2010), while the other, SA-MP, oscillates between about 15,000 and 50,000 concurrent players. It may be two Grand Theft Auto generations and 11 years old, but GTA: San Andreas is still very much alive.
