Here is the full list of all 35 Fallout Shelter achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Collect 20 Legendary outfits
Collect 20 Legendary weapons
Complete 100 Quests
Scrap 500 items
Make 25 babies
Build 1 of every room type
Complete 100 objectives
Level up a Dweller to level 50
Craft 1 of every room theme
Change the appearance of 10 NPCs in the Barbershop
Successfully stop 50 Raider Attacks
Successfully complete 50 Room Rushes
Complete 60 Quests
Craft 10 Outfits
Collect all Pieces of 4 Themes
Upgrade 20 Rooms to Level 3
Craft an Outfit, a Weapon and a Theme
Collect 100 Stimpacks and 100 Radaway on Quests
Build 50 rooms
Collect all Pieces of 1 Theme
Make 25 Dialogue Choices in Quests
Complete 30 Quests
Level up a Dweller to level 25
Kill 500 enemies on Quests
Craft 10 Weapons
Complete 10 Quests
Kill 10 Quest Bosses
Build 25 rooms
Collect 10,000 Caps
Level up a Dweller from 1 to Level 10
Merged 3 Water Rooms
Merged 3 Food Rooms
Merged 3 Power Rooms
Collect 1000 Caps
Collect 20 Legendary Dwellers