Unfortunately, there is no two player in GTA 4 if your not playing online. You cant hook up to controllers like you could in GTA San Andreas. But if you mean two players online, than all you have to do is bring up Nikos Phone menu and scroll to Multiplayer.
only for xbox and go to your phone it will say 2 players
there is no GTA4 on ds, but there is gta:chinatown wars on ds, psp, and ipod which is set in the first 2 islands of gta4, but in birds eye view.
only one human player.
mafia is more popular
Just Cause 2
You don't have turn signals on GTA4 usable by the player.
there is no hovercraft in gta4
just cause 2
no, but nice try.
check them out on the garage at gta4.net.
I haven't heard much about Mafia 2 or Yaquza 2, so I would say either GTA4 or Saints Row 2. GTA4 is very good, I own it, but Saints Row 2 is sure to be a biiig hit.
this is just my opinion gta4