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