Only one, it is a single player game and an online multiplayer game. More information on the game is available at both the walkthrough and related link.
EDIT: If you mean by multi-player online, then up to 16 players can be in the 'lobby' at once, and 8 altogether in a posse.
No :)
Millions.
yes can but one of you has to be the zombie.
you cant. until dlc comes out.
Splitscreen, unfortunately no. However you can play with a lot of players in different modes over Xbox Live or the PlayStation Network.
No, PlayStation 3 and Xbox 360 players cannot play Red Dead Redemption together due to the lack of cross-platform support. Each console operates on its own network, meaning players can only engage with others on the same platform. Therefore, PS3 players can only play with other PS3 users, and Xbox 360 players can only play with fellow Xbox 360 users.
you need red dead redemption to play outlaws to the end
Yes, you can play Red Dead Redemption on PS4, but only through the PlayStation Store's PS2 Classics section, as the original game was released for the PS2. Alternatively, you can play Red Dead Redemption 2, which is available natively for the PS4. However, the original Red Dead Redemption does not have a dedicated PS4 remaster or port.
You can only play Red Dead Redemption on your Xbox 360 or PS3 on the Xbox Live or Playstation Network
You can't play coop on Red Dead Redemption or Undead Nightmare.
No, you mnust be online in order to play Red Dead Redemption multiplayer.
around 1 to 4 player can play dead islaND CO OP