Here is the full list of all 20 John The Zombie achievements.
Win the third race.
Win the second race.
Win the second horse challenge.
Win the first race.
Win the first horse challenge.
Finish the campaign.
Catch one big fish.
No agressions for 10 minutes.
Score 2000 points by causing chaos.
Score 1000 points by causing chaos.
Score 500 points by causing chaos.
Score 50 points in basketball.
Learn 10 skills.
Kill 20 zombies with a car.
Attack 5 cops.
Eat 10 cow's brains.
Eat 50 brains.
Eat 30 brains.
Learn 5 skills.
Eat 10 brains.