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