Turn a human into zombie
Die for the very first time
Turn 10 soldier into zombies
Lose a zombie
Finish the game
Collect 20 stars
Collect 40 stars
Collect 60 stars
Beat all summer levels with total time lower than 15 minutes
Beat all winter levels with total time lower than 8 minutes
Collect 90 stars
Finish all winter levels
Play at least one community level
Turn 10 soldiers into zombies
Finish all summer levels
Turn a human into a zombie
