It is advisable that you do this in the jungle area. Avoid the power ups as much as possible and a lot of monsters will spawn. They will begin to do so when you get a score of about 4,000 to 5,000. The early spawners will be easy to jump on, but some might be tough because there are either too many of them or there are not enough platforms to assist you. In cases like those, you just have to shoot or get past them. More will spawn. Be consistent, patient and persistent and you will be able to unlock this achievement.