Unlockable: Minigames, Levels and Hats
Set the player 1 name to ROYGBIV.

Unlockable: Top Hat
In the Options Menu, where you can rename your alien, enter Grrl.

Unlockable: Diamond Tiara
In the Options Menu, where you can rename your alien, enter Abe

Unlockable: Daisy Headdress
In the Options Menu, where you can rename your alien, enter Princess or Betty.

Unlockable: Dick Tracy hat
In the Options Menu, where you can rename your alien, enter Dandy.

Unlockable: Blond Hair
In the Options Menu, where you can rename your alien, enter Cletus.

Unlockable: Red Hair
In the Options Menu, where you can rename your alien, enter April.

Unlockable: Pirate Bandana
In the Options Menu, where you can rename your alien, enter Goodman.

Unlockable: Super Soviet Missile Master mini-game
Finish level 1-5 and the Super Soviet Missile Master mini-game will be unlocked after the intermission sequence.

Unlockable: Area 51 Hat
Get to level 3-1.

Unlockable: Jouster Hat
Beat Level 3-4 using hard difficulty.

Unlockable: Private Eye Hat
Beat Level 3-2 using hard difficulty.

Unlockable: Soviet Union Hat
Get to level 2-1.