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