1) It's not that hard to figure out with a little deductive logic. Or just look it up. Or ask. Instead of this kind of thread, which ultimately serves no purpose other than to waste your own time while getting you no closer to your goal.

2) I'm unsure what you mean by a "loner's" game. Do you mean you're under the impression that it is a Single Player game? It's not. It's a co-op game, and designed around co-op. It's not a PvP Battle Royale though, so I guess there's that.

Perhaps you simply missed that you can invite friends into your game?