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