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