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.
Grow all plant types
Play through entire game without killing or eating animals. Alone in Single Player or together in Multiplayer.
Cut down 1000 trees
Revive 10 co-op players
Eat an entire family
Kill all animal types and display heads
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Eat an enemy
Eat all mushroom types
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Chop up 50 bodies
Share a weapon in MP
Share a food or drink item in MP
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
In Single Player, kill 100 cannibals
Build a super long wall
Finish Game
Set off 20 bombs
Make and wear stealth armour
Killed downed enemy with rock
In Single Player, don't kill any cannibals for more than 10 days in a row
Revive one co-op player
Collect all cassette tapes!
Kill bird with arrow
Use the compass
Sleep on yacht
Survive 5 nights
Kill shark. Alone in Single Player or together in Multiplayer.
Cut down 100 trees
Sleep with another player (group sleep)
Survive 1 night
Kill a bunny. Alone in Single Player or together in Multiplayer.
Craft all items
Craft 10 medicine items
Explore all caves
Find all missing passengers
Pass 50,000 steps
Repair a shelter
Collect all robot pieces