Hello. I am a former Rockstar game dev. I will not give any more personal information for my safety. My boss was a major D*** so this is why I am leaking info on the up coming Red Dead Redemption prequel.
The sequel will be called Red Dead Redemption 2: Legends of the West. Although it is the second (or third if you consider Undead Nightmare a sequel) game, It is chronologically before the original game. The game will take place in the same area as the original game, twelve years before the first original game.
There will be three playable characters, two of which are from the original game and one will be completely new and will not have much story line, Ill explain in a second. The two "main" characters are Irish and Seth. Irish will be brought up in Ireland and will move to the Americas when he is fifteen and moves to the game setting when he turns twenty one. Seth is from Kansas City and works as a teller in a bank. He then hears of a treasure and uses his life savings to bring his family to Texas in the town of Tumbleweed. Throughout the story we experience him unraveling to his state of mind in the original game, losing his wife, children, home, and possessions to his treasure. The third person is a character you create similar to multiplayer in GTA V. You choose his clothes and horse.
Although you can unlock outfits for Seth and Irish, the third person (Who you name) can acquire all different kinds of Western tops, bottoms, boots, gloves, and hats. Horses will also bring completely new customization to the game. You can choose there type/breed like the last game, but now you can also choose what saddle they have (with their own boosts and stats), storage, and paint. You can also buy your own safe house and customize it. Also, all of this carries over into multiplayer. There will be many new and more thought out stranger missions as well as roughly thirty campaign missions for both Seth and Irish. The third character can be involved in the campaign, but can not be used in missions. He will appear as a "gun for hire" and works with Seth and Irish, tying the stories together.
"You" (the third character) will be in free roam, but Irish and Seth can be called in as companions (but not be played as), as well as other people. You will meet many of the characters from the original game including young Bonny Macfarlane, Sherriff, and even John Marston, but he will still be in his gang.
A big new part of the RDR prequel is the new gang system. You can join several different gangs, or if you think you are up for it you can join the law enforcement of certain towns, but this will restrict you on things you can do like robbing. Although you can rob it might cost you your hard earned career and possibly your life. You can also bring in a posse (up to 4-8 friends) to single player, technically co op now. You can take on certain side missions and a few campaign missions with your posse.
RDR 2 LotW will be announced at the upcoming E3 event.
I don't expect you to believe me, but this is all true. I used to go to work every day and see this.
Thank you for your time, A former Rockstar employee and audio engineer