Here is the full list of all 45 The Forest achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Build a super long wall
Pass 50,000 steps
Cut down 1000 trees
Collect all cassette tapes!
Finish Game
Set off 20 bombs
Make and wear stealth armour
In Single Player, kill 100 cannibals
Revive 10 co-op players
Cut down 100 trees
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Kill bird with arrow
Use the compass
Share a food or drink item in MP
Revive one co-op player
Sleep with another player (group sleep)
Kill a bunny. Alone in Single Player or together in Multiplayer.
In Single Player, don't kill any cannibals for more than 10 days in a row
Survive 1 night
Survive 5 nights
Eat an enemy
Eat an entire family
Share a weapon in MP
Craft all items
Kill all animal types and display heads
Grow all plant types
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Craft 10 medicine items
Sleep on yacht
Explore all caves
Killed downed enemy with rock
Chop up 50 bodies
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Find all missing passengers
Kill shark. Alone in Single Player or together in Multiplayer.
Eat all mushroom types
Repair a shelter
Collect all robot pieces
Catch fish with a trap. Alone in Single Player or together in Multiplayer.