To unlock the following, complete the following tasks:
Unlockable: --- How to Unlock:
2x combo multipler --- Clear 50 stages without using the Mince Grinder
Bigger Zombie Crusher --- Clear 50 stages without using the Zombie Crusher
Easier Hell Fire --- Clear 200 stages
One-Hit Kill --- Kill 25,000 zombies.
Keep in mind to utilize the 'A' button to slow the ball down and alter instructions, therefore getting as numerous zombies as possible. If the alarm bells are ringing, constantly go for the zombie nearest the front.