The below information is by no means concrete. It's a supposed leak from Game Informer's December 8th issue. I'm just recycling what I've come across.
So to begin our main protagonist will be 42 year old half-American, half-Puerto Rican male named Albert DeSilva. Apparently, he's hit a bit of a crisis in his life. Divorced, with two kids and having lost his money in a get-rich-quick investment scheme he seems in a state of relative disrepair. As all good middle aged Puerto Rican-Americans do he's decided to recoup his losses by turning to crime.
Albert isn't the only character you'll be carrying out dubious activities with. As the game progresses you'll play as Dougie Vejo, a criminal somewhat younger than DeSilva from the Los Santos. Nothing's really known about Dougie as of yet. I'd imagine we'll see some more information coming soon.
On the topic of characters, we're set to see some GTA IV cameo appearances. Who the characters are isn't currently known, but my personal guess says it won't be any of the playable protagonists. The only playable character we've seen resurface in the past is Claude, and we all know how chatty he was. It hasn't been announced, but I'm guessing we'll see some old San Andreas favourites crop up too; it will be set in the same area after all. It has been said that Grove Street will see a return, but the Johnson brothers will not. I want to see Big Bear running the gang, personally.
Customisation will be included in this game too. Unfortunately, the gym and tattoo dynamic will not see a return, but some others will. We’ll be able to style DeSilva’s hair/facial hair and give him a dapper outfit to match. It’ll also be possible to customise cars, however the extent of which is currently unknown.
As seen in the initial trailer there’ll be some minigames for us to enjoy. So far golf, tennis and surfing are set to be included but there may very well be more.
Finally, 4 songs have been confirmed: My Michelle by Guns N’ Roses; Magic Power by Triumph; California Dreaming by The Beach Boys and Beautiful by Snoop Dogg feat Pharrell. With any luck we’ll see a playlist more like that of San Andreas than that of GTA IV.
So that’s it for today. I’m sure we’ll see some more interesting information surface soon. We'll be sure to try and get it to you guys as soon as possible when it does.