You need to be online to actually play, but I spent most of the first Destiny effectively in “single-player” mode. You get missions that pop up on a big map and if you haven’t already selected a team when you hit start it just drops you in alone.
There are a few that require either 3 or 6 players, and if you aren’t in a team it will find random people around the same level if possible. I don’t think any of those are required to unlock the main mission progression though.
I did a few of these without any voice chat and got pretty lucky in terms of having partners who didn’t run on ahead or get lost. One time I was the one who got lost and I could see the other two guys fighting this huge monster while I tried to find the staircase to get to the boss area, finally running into the room and firing off a single rocket as the boss died. I still got all the same rewards as the other two, so I just kind of stood around trying to look useful until the mission end screen popped up and then logged off.
Any ammo or items get duplicated for all players in the area, so you don’t have to rush over trying to grab the loot first, and you’ll get points just for showing up as long as someone gets the job done. There are tournament modes that I never looked at, but you can be pretty laid-back and ignore the multiplayer aspect most of the time.
