Destiny developer Bungie has clarified that you'll be able to play through all of the game's story missions in single-player if you want.
"You aren't required or forced to play any story missions in Destiny as part of a co-op group," clarified Bungie community manager Eric "Urk" Osborne on NeoGAF.
Osborne's response comes after an interview with Bungie's Jason Jones on Game Informer, which led some people to believe that some of the shared-world shooter's story missions would require co-op play.
"You absolutely are going to be able to play Destiny by yourself and have the same kind of fun shooter-experience that you could have in a single-player campaign," said Jones, "which is a word that we’ve weeded out of our vocabulary, but we’re going to give you this great player-progression on top of that, and we’re going to give you as many opportunities as we possibly can to expose you to other people, so that hopefully you’re drawn into some social experiences, because those are incredibly powerful and interesting, but we’re not going to force those on you."
Jones added that some of Destiny's end-game content, such as raids, could require co-op. "We describe it in a lot of ways as sloping the floor towards socialization, without putting a requirement on it. I would say that there’s some sort of--if you wanted to talk about it in MMO terms, you’d say 'end-game activities', but some of the most intense non-competitive activities in the game do require co-operation."
"They require a group of players to tackle at once. I guess at some variable, distant endpoint we are going to say, 'Yeah, if you show up at this door, and you don’t have five friends, you’re not going to be able to succeed,' but the core experience that solo players have enjoyed in shooters, they’re going to be able to get that, and we’re going to pull many of them into social experiences as well."
Destiny will be released for Xbox 360, Xbox One, PlayStation 3, and PlayStation 4 in September 2014.