Area 51 Hat
Get to level 3-1.
Blond Hair
Beat the final boss on Hard mode.
Curly Hair Wig
Blow up the Fish are like plants building in level 1-5.
Dimond tirera
Beat level 2-2 on Hard.
Extra life
When there is a flower in the ground dig next to it and you will get a life.
Hidden Hats
In the Options Menu, where you can rename your alien, use the following names to unlock hidden hats for the 2 player game:
* cletus
* april
* superfly
* goodman
* grrl
* abe
* princess
* dandy
Jouster hat
Beat level 3-4 on Hard.
Level 3-4: Extra lives
After fighting the Boss (giant green robot with the eye and a fork and knife) and his life reaches zero, he will start exploding. Continue shooting at his eye. He will just continue exploding as long as you shoot, and you will continue gaining points. You can stop when you have about 60,000 points. At the end of the level, you will gain about eventeen
lives.
Pirate Hat
On level 1-1 destroy Hairy Nanny Daycare right after the miniboss.
Private Eye hat
Beat level 3-2 on Hard.
Soviet Hat
Get to level 2-1.
Tom Fulp hair
Name your hominid tomfulp.