Here is the full list of all 20 Sven - there are Completely Screwed achievements.
Successfully finish 69 levels in total
Mate-call 69 sheep
Mate-call four sheep at once
Be on the receiving end 69 times
Get caught 50 times by Wotan or Lars
Get shocked by a devil sheep
Get away from Wotan 25 times
Make 10 Sheep vanish in 30 seconds
Reach 1200 points in a level
Reach 1600 points in a level
Score 2000 points in a level
Complete every level successfully at least once
Complete all levels in a row without dropping below three lives
Complete three levels successfully in a row
Complete five levels successfully in a row
Complete all levels successfully in a row
Unlock your first position
Unlock all positions
Use Items 69 times
Used every position at least once