Dead Rising

Great solution by Xv iLeGenDzZ vX

I used a slightly different method. There are 3 cars in the maintenance tunnels that you can use to maximize zombie deaths for this achievement. Here's my method:

(1) definitely grab some OJ and the horror 2 book as mentioned by Xv iLeGenDzZ vX
(2) head to the maintenance tunnel entrance which is accessed by going through the park
(3) get in the red convertible and enter the tunnels
(4) take an immediate right, then a left, then a right, then a left which will put you at the white car
(5) get in the white car and follow the attached map: right, left, right, left again which puts you at the white van
(6) get in the white van and drive the loop
(7) head up the ramp and get in the red convertible again

I averaged about 1200 kills per loop with this method and managed to have lots of fun despite the repetition. Your zombie mileage may vary

Helpful map here: http://imgur.com/sYZ93R2

I marked the maintenance tunnel key on the map as well ... if you want to save during your run at this achievement make sure you get the key then head up the stairs by the white car to put you back in Paradise Plaza right by the bathrooms for a quick save. When you re-load ... head down the stairs and start with the white car.

Zombie Genocider requires you to kill 53,594 zombies in one playthrough of the game. You are going to need around 3 hours to complete it.

To start the achievement start a fresh playthrough, and once you set foot in Paradise Plaza go to Bachman's Bookporium on the ground floor and pick up the Horror 2 book, which boosts PP from zombie kills by 25%. Then grab some Orange Juice from Colombian Roastmasters upstairs just in case you need to heal while obtaining the achievement.

Now head to the western side of Leisure Park, and look for a little alley to a parking lot (look on the map for a car symbol). In this parking lot you'll find a motorcycle and a red car. Here is where the method begins.

Drive the red car into the Maintenance Tunnels, go left and follow all the way to the end, killing as many zombies as possible. Try to hit propane tanks to maximise kills as well. Once you hit the dead end you will see a large group of zombies, so drive through them, then reverse into them, and repeat until the car breaks. Then get into the white truck and drive it back out to the parking lot, and repeat the process again. You should get 500-600 kills per trip.

Every 1,000 kills you will get 25,000 PP as well, which will level you up fast. I hit Level 30 during my attempt, starting from Level 1. Make sure to save frequently during this as well, as the Xbox has a habit of crashing.

Once you have the achievement, remember to get an ending to unlock one of the best weapons in the game, the Real Mega Buster. You should have a day left to play once you have the achievement (I had around 30 hours), so use the remaining time to get some other achievements, such as Gourmet, Clothes Horse and Karate Champ.

To add to any of these solutions, when you are heading towards the white car make sure to take a right where the maintenence area is just to spawn 300-400 zombies. If you back up and hit the canisters that blow up you will net the kills in about 5-10 seconds and doing my runs I was getting 1300 kills per 3-car cycle...... In 4 minutes

Lastly, remember to save. My game crashed just past 25k kills.

Personally i would get the ceevo on your 1st play through. As it will level you up so you have more health & you can carry more items.

Play the game for 10-15mins till you can get access to the horror book from Bachman's Bookporium, its at the start pretty much when you can move around the plaza. Take the exit north of the store(Paradise Plaza exit) to bring you out onto the Leisure park.

From here walk to the direction of Wonderland Plaza but dont go in turn right an you will see a opening to take you to car 1(red car), follow The Guild of Awesome(vid cred) route.

Get the maintenance key to make a save every 5k kills(i used the doorway at car2/white car). Follow RKOJPL7 method how to get it(vid cred)

I had 33 game hours left. So keep playing going for none story ceevo's to drain down time to get an ending to keep your stats for a main game play through.