SAS: Zombie Assault 4 is a pretty solid game and worth playing.
I have had a lot of fun playing this fast paced and chaotic shooter; however, if there was one thing I would have to say, or complaint about this game. It is the fact that the pre-lobby, at least in nightmare mode is always unbalanced. In fact, the more senior players of the ZA4 community do not want to give the low level +35's a chance because the level +35's are actually newbs, a liability when it comes to playing nightmare mode.
Perhaps these higher ranked players have put in the time, effort and have gone through the same exact thing that all level +35's (which is what level nightmare mode unlocks) have going through. But, it would be nice if 3 senior players were paired with a level +35 in an attempt to balance the significant experience imbalance that exists within nightmare mode lobby's.