Kill 20 zombies in FPS mode
Research a new tower
Build 100 towers
Build an arms factory
Complete the tech tree
Extinguish 20 pyro zombies by freeze ray
Call an early wave
Build the lander shield
Kill 200 bomber by laser tower
Stop 10 runner zombies by freeze ray
Deactivate 30 electro shields by tesla
Use all monoliths in mission 20
Kill 2.500 zombies
Build a tech center
Kill 25 zombies at once by nuke
Kill a mutated crew member
Kill 10.000 zombies
Earn 5 perks
First special force
Earn all perks
Use 4 different super weapons in a single mission
Earn 1 perk
Build 50 towers
Max a tower
Unlock all achievements
Analyze all monoliths
Kill 1 zombie
Win a mission without building a tower
Complete all missions of the campaign in challenge mode
Complete the campaign
Take a screenshot
Use a super weapon
Heal a crew member
Build 500 towers
10 special forces in one mission