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