Lone Ranger Achievement
Killed every monster type once.
There are 10 enemies in this game that you need to kill. This can be either through jumping on their head, shooting them or using a power-up on them. You should get this by just playing the game but i will put a list of the monsters and when they first appear below. Bosses do not count towards this.
Dark Green monster
Blue/Purple flying monster
Three headed green monster
Dark/light green fluffy monster
Once you have killed one type of each monster you will get this achievement.