You cannot join an already in progress mission (at least i cant see how to join an in progress one) Whenever you start a mission you have the option of doing co-op, which lets you either invite a mate, or wait for a random to join your game or you his. (there seems to be 16 side missions, 2 of them pre-order bonuses, so future dlc :'( ) It's is barred from the main levels due to the co-op character being an npc in some of the missions. You have probably found out by now, but just in case.īy the looks of it you can only any of the side missions.
