I had fun with it 2 player. We figured out how to open PaP but it took us a while. We thought maybe the poster on the wall by D-Tap was hinting to get a bolt action sniper rifle and hit the bullseye so we tried that up to round 20 or so lol. We each got a different version of that invisible OP gun, then PaP'd them. After giving up on figuring out an ending, we camped in the power room, only leaving for drops. That was crazy fun.