it's an open world game. You'll have the story / campaign, which details your initial effort to escape the city, meeting the factions like Troop Bushido and the Fargarths and your interactions with them, and so on. That's going to have missions that each have some unique and cool stuff - like fighting Fizzie or riding on the roller coaster (both of those are examples of campaign missions). The campaign has cutscenes and full voice acting for your character (male OR female voice)
There are also quests, like helping the guy at the comic-store track down the comics he loaned to people (who are either now Scabs or OD). Not integral to the story, but many times give the backstory of the world and people.
and of course you have challenges too, like smashing a ton of TVs with only your melee weapon within a certain amount of time.
oh and there are collectibles too. a whole economy, amps to craft (for which you'll need to find recipes and ingredients)
plus Chaos Squad, where you can jump online with your SP character exactly as is and team up with 7 people online to tackle missions in the open world before taking on a defense of one of your bases in the city - great loot and rewards here you can bring back to your campaign.
There's lots to do!
