First up: there's a season pass because this is a modern video game being released by a major publisher. Included with that $40 purchase is access to two expansion packs ("Narco Road" and "Fallen Ghosts") a week ahead of everyone else, some other missions, cosmetic gear and consumables like XP boosts.
But, everyone will gain a 4-on-4 player-versus-player mode for free. Need something to hold you over until next Tuesday? That's what the trailer embedded below is for. One scene shown from the "Narco Road" expansion looks an awful lot like Rust Cohle's journey back into the underworld from True Detective season one, if you ask me.