Its deffinitly 2 player, I was playin it with me mate the other nite, when you get ya first girlfrend ( Denise ) who is literally a 5 sec walk from you house in Grove St. ( she appears as a heart blip on the map ). Sometimes, at night a red marker ( them things that trigger missions ) will appear in front of her house and you can take her out on dates etc.
If you look right on her doorstep, there is a red icon which resembles two little people, if you go onto it, press a button on the second analog controller connected to your PS2.
I have heard that you can activate two player the same way but in different areas of the map, one 2 Player icon is under a bridge in Flint County ( so I heard )
Also, when you have a pilots license, goto Easter Bay Airport and let a player get into the plane. As two people cannot get in the same plane for some weird reason, let the other player jump onto the wing of the plane you want to fly. This works best the The 'Juank Air' < (or something similar ) plane, its a Jumbo passenger carrier.
B careful for one of you not to fall out or off the plane otherwise the players will b too far apart and the 2 Player Game will end.
Me and my frend both jumped off the player together and landed in the sea at the same time, it was SO cool man try it!
Good Luck to all you GTA Gamers out there!
- ZEDDY
Then again, that's mainly because I have dial-up internet connection 
