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.
Find all missing passengers
Collect all robot pieces
Kill all animal types and display heads
Eat all mushroom types
Collect all cassette tapes!
Finish Game
Revive 10 co-op players
Chop up 50 bodies
Kill shark. Alone in Single Player or together in Multiplayer.
Eat an entire family
Build a super long wall
Set off 20 bombs
Cut down 1000 trees
Share a weapon in MP
Use the compass
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Craft 10 medicine items
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Cut down 100 trees
Repair a shelter
Revive one co-op player
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Grow all plant types
In Single Player, kill 100 cannibals
Killed downed enemy with rock
Share a food or drink item in MP
Sleep on yacht
Make and wear stealth armour
In Single Player, don't kill any cannibals for more than 10 days in a row
Survive 5 nights
Sleep with another player (group sleep)
Kill bird with arrow
Kill a bunny. Alone in Single Player or together in Multiplayer.
Eat an enemy
Survive 1 night
Craft all items
Explore all caves
Pass 50,000 steps