I think the boss battles in this game are hard and repetitive. What I mean by this is that whenever you kill a zombie in a boss stage another one comes almost instantly. This get very annoying as you are trying to kill the zombies that are blocking the boss and when you do kill them they come back and start blocking the boss again causing so much rage and frustration. I personally think that whenever you kill a zombie in the boss stage, they should have a delayed respawn preventing this problem. Thank you for reading this and I hope you fix this annoying problem.