Here is the full list of all 21 Woah Dave! achievements.
Collect five hundred pennies!
Defeat the mothership in West Haven!
Collect four hundred pennies!
Defeat the mothership in Fort Bragg!
Ride a UFO!
Defeat the mothership in Peoria!
Kill a rare alien!
Collect three hundred pennies!
Collect two hundred pennies!
Let a Woah Block get blasted by a UFO!
Get killed by a UFO beam!
Your name is POO!
Let two platforms get blasted by UFOs!
Throw a Woah Block in the Lava!
Kill a UFO!
Destroy a Woah Block with another Woah Block!
Kill 10 or more enemies with 1 Woah Block!
Collect one hundred pennies!
Hit an Eyebat!
Earn your first penny!
Collect one thousand pennies!