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