I will say joining up against a common foe is good for morale and good for low numbers on a server. Games just like sports, conversations, dances, or films can’t be constant high intensity. There needs to be some relief, or intermittent rest/slow down. (It also helps new players hang in there longer than me and Catting or Totd vs kitkat59 and likesburritos) Lastly co-op makes me miss gunnie and his crazy co-op ideas. (I also miss Shocky Gonzalez but that is a story for another time)