Here is the full list of all 14 Lovely Planet achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Collect All Gun Colors
Find All Hidden Secrets
Visit the Shrine of Lovely Planet
Find the Hungry Samurai (Village)
Drink the Sake (Swamp)
Find the Dagger with the Pearl Inlay (Forest)
Unlock All Stars (Mountains)
Unlock All Stars (Swamp)
Unlock All Stars (Forest)
Unlock All Stars (Village)
Shoot Yourself
Find the Graves (Village)
Unlock All Stars (City)
Parry Projectile at Right Angles