Here is the full list of all 14 Grandpurrents achievements.
Complete 1000 floors
Complete each floor once
Complete all floors in one run
Finish your first floor
Save all of the cats
Finish all floors as Grandma
Finish all floors as Grandpa
Complete 10 floors
Complete 100 floors
Kill a boss without taking damage
Complete a floor without taking damage
Complete all floors without using any cat perks
Complete all floors without a pickup
Complete all floors without taking any damage