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