Full list of all 20 Angry Birds Classic achievements worth 200 gamerscore. It takes around 40-50 hours to unlock all of the achievements on Windows Phone.
Three stars collected in all levels of the episode
Angry Birds played for 30 hours
Angry Birds played for 15 hours
5,000 birds shot
Angry Birds played for 5 hours
Secret Cake collected
Boomerang bird unlocked
Big brother bird unlocked
White bird unlocked
Black bird unlocked
Yellow bird unlocked
Blue bird unlocked