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