Here is the full list of all 20 Dungeons & Geese achievements.
Defeat Boss in 1'st location
2nt Ending
3rd Ending
Solve the mystery behind Old's Man Bankruptcy
4rd Ending
1st Ending
Complete the Game
Defeat Boss in 3'rd location
Complete 36th level
It's better than goose saddling you, isn't it?
Collect 100 Pink Spears
Defeat Boss in 2'st location
Complete 18'th level
Collect 10 Heal Items
Meet Lacroix in Heaven
Collect 50 Blue Spears
Kick out all guests from the ball
Complete 1'st Level
Run the game