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