As far as horde, you can only play on split screen. If you're co-oping the story, you should be able to play on 1 screen. Are you playing the story or Horde?
That's funny, cause I just started playing horde this weekend. The first game I played, I started, I was first guy there. By the end of the second wave we had 5 guys and we played all the way through 50 waves.
Then started a new game, again was first guy in and got 50 again.
Tried several times more and never got a good group again, but I have since heard how rare it is. to get 50 in one shot like that. And to get it with randoms twice in a row is really rare. Communication seems to be the key. Yes I have a mic BTW.
If you don't believe me, check my stats. 2 different 50 wave achievements in 1 day.
Anyway I'd be up for some horde if anyone is still interested. I'm usually on from 3-5 PM EST most days.
GT = capta1n0bvious3