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