Here is the full list of all 20 Ferrum's Secrets: Where Is Grandpa? achievements.
Finish game on any difficulty level.
Find all scientists letters.
Fly over the city using the aeroplane.
Find Lagrange family tree.
Find Fatal Blast project payroll list.
Find water of life in Doris' house.
Find all grandpa's notes.
Feed Blacky, grandpa's kitten.
Chase a spider in the grandpa's basement.
Finish steam leakage mini-game.
Find your first collector's item.
Find all collector's item on normal difficulty level.
Find all collector's items.
Finish game on extreme difficulty level.
Finish game on all difficulty levels.
Find all collector's items that are paintings.
Find 5 collector's items that are made of glass.
Finish all mini-games without using Skip button.
Finish game without using any source of light.
Finish game without finding any map.