Tip to help with turrets on killer diff
The turret sections were very annoying to me and i found out a way to beat them with much ease. With the first one where u r protecting the girl just take each guy out slowly by aiming the gun up then lowering it to shoot a guy one at a time, aiming the gun up protects you from shots. With the second turret lvl just shoot guys till you are about to die then aim up, you should last the 2 mins, dont aim up the whole time because the shield on the gun will eventually break off and you will get shot no matter what. I hope this helps.