It's a good game there's a few things that might frustrate you when doing the challenges like that I feel your pain challenge. Where if anybody on the squad takes damage you take damage to. It's really only and inconvenience so far on the key to the city map. That's if you have bots on your team because the bots stand in front of the gate where the zombies are trying to go and if one of your teammates gets damaged you get damaged. You will keep dying back to back or at least I did and if you die a few times in a row you have to start the whole level over should be okay with at least one bot on your team but if you have at least two I believe it to be almost impossible to get past the first stage of key to the city with that combination I don't really notice much else needing fixing. It's a challenging game I just suggest if you see that challenge on that map and you don't have any squad mates just play a different map and wait an hour to see a different map locations on The daily challenges.