Great game even if you're alone. There hasn't really been anything that has required multiple players to beat so far, outside of maybe one of the DLC sidequests. Liable to change with future updates.

Plenty of fun to be had without friends in this game. Probably won't be able to do everything in the game alone (NG+, optional things) but there's lots to do in the main game.

A funky game that's still very playable solo.

I've gone through this game probably about 6-7 times by now and a couple more times on 360. Co-op wasn't necessary to enjoy the game.

Has an "Offline Practice" mode that essentially lets you play the game with bots. The downside is the AI is sketchy and only works on select maps by default.

Minimal single player content. Bot AI is awful, too. Humans are almost mandatory.