Here is the full list of all 21 Woah Dave! achievements.
Get killed by a UFO beam!
Let a Woah Block get blasted by a UFO!
Ride a UFO!
Let two platforms get blasted by UFOs!
Kill a UFO!
Collect one hundred pennies!
Destroy a Woah Block with another Woah Block!
Kill a rare alien!
Your name is POO!
Throw a Woah Block in the Lava!
Kill 10 or more enemies with 1 Woah Block!
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!