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