Here is the full list of all 20 Goo Keeper achievements.
Killed The beetle boss
Killed The Boss Rumbus
Killed The Boss Rocky
Killed The Boss Mothgoo
Killed The Boss Kropus
Killed The Boss Sarnik
Killed The Boss Cogger
Killed The Boss Crysilith
Killed The Spider Boss
Killed The Boss Sumro
Killed The Boss Claymore
Killed The Boss Albatros
Killed The Boss Goorathur
Killed The Boss Seemore
Killed The Final Boss Omega
Finished The Game
Fully Completed The Game
Finished With Ironman Mode
Finished With Disabled Map
Killed All Bosses