You'll start in a classroom being attacked by a group of five zombies. It's kind of hard to bunch up the zombies because the room is so wide. It makes for good practice controlling he crowd though. Kill them and a sixth zombie will come through the back door. Kill him (simple) and head into the hall. You'll see an explosion and then be directed into the next classroom.
In here, you'll meet a teacher zombie who is particularly tough. Like the Hazmat team, they are a little different than regular zombies. However, before we get to that, you'll have to clear out a couple groups of students first. Kill the four in the room (try and get one nice big Sparkle out of them). When they are dead, eight more will enter from the door by the front. Again, try and bunch them up and go for a Sparkle Hunt. The room is wide and can make that difficult but it also gives you room to move around.
With the small zombies out of the way… the Teacher will run away. Go into the next hallway and follow it until you come to a section with a bunch of students having a rough day. There's only one student to save here, the boy at the far end of the hall. Despite wanting to fight your way down, just run straight over and kill any enemies nearby. He's sort of a lightning rod so take advantage of it and get some Sparkle Hunting going on. Just make sure you collect the Golden Lollipop behind him (on normal). When he is safe, head into the nearby room with the boy in it. Save him from the zombies but make sure you wait for your reward before you leave because if you move too quickly, you may not receive it.
With two students safe, move into the other room and you'll fight six zombies and Fitzgibbon. He isn't as hard as he might seem at first. Don't attack him from the front, he'll block with the podium/desk. Get behind him and hit him until he winds up to strike (he'll change colors a little). Just before he strikes, dodge behind him and continue the attack. Eventually, he will drop the desk and you can just wail on him. After you kill him, a zombie will blow a hole in the wall. Hop through it.
When you land, make your way to the cops until you are cut off. Then turn around and cut your way to the wiggling blue thing beyond. You'll be able to attach Nick's head to the body and then use it to move debris. You'll have to hit the buttons that appear on the screen as they appear to get him to move. If you fail too many times, you'll "die".
Once the wall is destroyed, you'll find another Chop2Shop and a Nick Ticket. The Nick Ticket will allow you to use Nick in combat. You'll only have one option right now but you'll get another which drastically increases your chances of winning. When you use it, a bar will appear at the top of the screen and you have to stop it on the ability you want. It can be quite useful if you're losing a battle but it's also easy to misuse it since it's on the L3 button and you might hit it by accident during combat. Shop if you'd like and then head down the hall.
Down a long hallway will be a student and some zombies. There are seven to kill and many, many lockers. You can use Nick if you'd like. Kill all the zombies and break all the lockers. After you save him, he'll disappear and you'll be left with a bunch of zombies. There are seven more. Kill them and make the most of it. The next time the door opens, be ready to make your way up the hall quickly. You'll be shot at and it's best if you keep hammering the dodge button as you make it up the hall. You'll have to get close and kill Ryu, the cop with the flaming baton. Once close, he's really not a big deal except that he can block your attack and you'll have to hammer the chainsaw button to win the deadlock that occurs. Once Ryu is dead, make your way through the shutter in front of you.
Once you cut it open, a student will run through and then two zombies. Kill the two zombies by hitting them once and running away. Check inside the room behind the shutter for medals and a lollipop. Head back to the hole in the wall that leads up a level. When you climb up, a bus will come at you. Run to the left side of the hall and saw at the column to knock it into the path of the bus. Now that it's safe, make your way up the hall to save the student hanging above you. Kill the zombies and then a zombie will blow a hole in the wall above you. Kill the next wave of zombies and climb the bus to get to it.
On the top floor, you'll make your way down the hall and then a couple of students will shut you out of the room. Go into the room on the right side of the hall and once inside, you'll be attacked by flaming zombies. You can't let them touch the students in this room or they will explode. A pole will drop down from the ceiling and if you use it, you can kill all 12 with ease. Jump on the pole and just start hammering on the chainsaw button. If you don't manage to kill them all, just clean up whatever is left.
Go out into the hall and open a hole in the shutter to your right. Make your way into the next classroom to find a student about to be blown up. You need to push the TNT zombies away from him so he doesn't die. It's important you focus on this before anything else. Once those TNT zombies are dead, you can deal with any stragglers. Once you've saved him, head to the next shutter. Cut that open and head through. When you are prompted to jump into the hole, you'll have to jump across the zombies heads. Just get ready to hit buttons when prompted to. It should all be one button for this first zombie walk section. Walk across them and then collect your medals. Now follow the hallway until you get to a wooden door. Cut through the door.
First you'll go through a trophy room with a Golden Lollipop on normal. The Lollipop is on the far side of the room from where you enter behind a trophy case. Collect it and go through the double doors. This will begin the basketball game. You'll have to kill zombies with your chainsaw which will send their heads flying into the hoop. After a little bit, a defender zombie will show up and swat balls away from the hoop. Make sure you kill him when he appears because he'll stop almost everything. After you get to about 70 points or so, cheerleading zombies will show up. Where you used regular chainsaw attacks on the players, use low cuts on the cheerleaders until you score points with them too. As soon as your score surpasses that of the zombies, the game will stop and the door will open.
When you enter the next room and try to cross it, a zombie will roll in strapped with C4. You need to go through the door that he came in through to escape in time. Get into the next hall and you can go shopping. In the hallway after the shop, you'll be attacked by 10 zombies in a rather small space. Use the tight confines to get a Sparkle Hunt or two. Kill them all and then go into the next room. There's a lot of desks and smoke in this room but lots of space too. Use the space to your advantage and get some space between you and the zombies so you can line up some Sparkle Hunts.
After killing them all, a blue zombie body will appear for Nick. Do the mini-game to open the door. Two Zombie Cops will come through and one of them is named Stephanie. Try to keep them close together and then get right up on top of them so they don't shoot you. Kill them both with aggressive attacks and then go through the door they came from. Make sure you get the lollipop in this room before you leave.
The next hallway will form a sort of arena. Inside, you will be trapped by two shutters and zombies will pour in a little at a time. You'll start with some on the floor and in lockers. The area is tight so try and get some groggy zombies going. When you kill off this bunch, you'll be attacked by more zombies. The fire zombies will run towards the bomb zombies and everything will explode. Just hit one of the bomb zombies to start the fireworks early and run away. One last group of zombies will appear. The greasers come back and some of them have guitars which can stop your chainsaw in a deadlock. The shutter will open and you'll just have to kill the one zombie who kept opening it.
Once he's dead, go through the next shutter and shop if you'd like. Go up the stairs to your left. When you regain control of Juliet, you'll be in a fight with 14 zombies. There's a Golden Lollipop in one of the corners of this room. If you can use your special, this is a good time to use it. Use it and get lots of Sparkles. After the regular zombies are dead, inspect the cake and then they'll start throwing flaming zombies at you, one at a time. You'll have to kill them before they reach the TNT or everything will explode. At certain points, you might have to juggle them rather than kill them outright.
Eventually, a bunch of exploding zombies will roll in and you'll have to roll out the front door. After another cutscene, you'll be in a boss fight with Zed. First you'll have to get close to him. Make your way along the path. When Zed starts throwing letters at you, try and dodge your way forward. When the path turns left, you'll come across a few weak zombies. Kill them and continue on. When you are shown a car hanging from a crane, get ready to hit the chainsaw button.
Once you get past the car, you'll have to dodge more words and then cut through a red car. You'll end up in a small area with six zombies. It's probably easier to see if you go to the far side of them. From there, the camera angle is better. Make use of the small space for medal collecting. Kill them all and then open the fence to continue on.
Go through the fence and slide down the pole. Make your way along and through the next barrier. After that, you'll have to dodge a bunch of cars and poles. Slide down another beam and then cut the one that tries to fall on you. Carve the car that falls towards you. When you jump off the edge of a school bus onto the stage, you're ready for the real battle.
The first round will see Zed running circles around you and then either making a lunge towards you or and overhead swing. Either way, just keep dodging to the side until he swings, then close in for some serious damage. After this happens a few times, you'll be told to "Finish" him. Go up to him and swing your chainsaw at him. You'll then be prompted to push a direction and repeatedly tap the chainsaw button. Do as prompted to start the next phase.
A bunch of small speakers will fall from the sky and Zed will be on one of them. Swipe at them to destroy them. Zed will shoot energy balls at you so be sure to dodge. Once he shoots them at you, close in on him and hit the speaker he's on. If you wait too long, he'll drop more speakers and move to another one. You need to destroy a couple speakers and then get to him before he does this so he doesn't drop any more speakers. When you finally destroy all of the speakers, a giant speaker will drop out of the sky. He'll stand on top of it. Go up to the speaker and cut across it horizontally. While you do, he'll attack you from the top. Make sure you dodge his attacks and then resume cutting. Keep going until you cut all the way through, then kick it over. He'll fall off and he'll get another "Finish"
Now Zed will move around or hover in place. When he is still, he's charging his energy balls again. Wait for him to shoot them, dodge and then close in on him. Momentarily, the balls will come back at you and you'll be prompted to dodge. Do so to cause damage to him. Hit him with those energy balls 15 times for an achievement! When he's running around, be careful because he's going to do a physical attack very quickly. Just keep dodging until he swings. Once you have the achievement, wait for him to attack one way or the other and then attack him. Soon, you'll get your last "Finish". Oblige to finish the fight.
*Achievements: Watch Out for the Balls.
*Achievements: Zed is Dead, Baby. Zed's Dead.