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