Here is the full list of all 31 Stranger Things 3: The Game achievements.
Beat the game on New Game+
Found all 50 hidden gnomes.
Complete Store Raid
Found 25 hidden gnomes. Half-way there!
Complete 30 Minutes or Less
Complete the game
Complete Mall Showdown
Complete Cabin Ambush
Complete Invasion of Privacy
Unlock Steve
Unlock Erica
Unlock Will
Complete Chores for Granny Perkins
Complete Hospital Brawl
Craft 5 trinkets
Complete Rats in the Walls
Successfully hack the hardest level chest/door
Unlock Hopper and Joyce
Unlock Eleven
Complete Ivan the Smuggler
Unlock Max
Complete On the Wire
Complete Revenge of the Geeks
Complete Break In, Make Out
Complete Wall Flower
Unlock Jonathan
Unlock Nancy
Complete Radar Love
Crafted your first item
Unlock Dustin
Complete Sneak Peek