It seems there is still some confusion about the presence of the two player mode in the PC version of San Andreas. The PC version won’t have a two player mode, which we haven’t stressed up until this point because we assumed people had read the previews that we’ve written about.
Now in case you missed it, and it seems a lot of people did, one of the previews we reported on earlier had this to say about the two player mode.
Unfortunately, the two-player missions of the console version have been axed due to technical reasons. According to a Rockstar rep, Direct X does not support two input devices of the same nature, so it would be impossible for players to use two keyboard and mice or two gamepads to execute these missions. Rather than force each player to use a different control method, the decision was made to cut the feature. This is the only omission to the game, and as an Internet multiplayer mod is already in the works, it’s doubtful that these missions will be missed for long.
However unlikely the two player mode was prior to this preview, I think it is now safe to give up and accept the fact.