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.
Find all missing passengers
Explore all caves
Pass 50,000 steps
In Single Player, don't kill any cannibals for more than 10 days in a row
Build a super long wall
Cut down 1000 trees
Eat all mushroom types
Craft all items
Kill all animal types and display heads
Kill shark. Alone in Single Player or together in Multiplayer.
Craft 10 medicine items
Knock down 6 or more trees with 1 explosive. Alone in Single Player or together in Multiplayer.
Repair a shelter
Grow all plant types
Kill 6 or more fish with a stick of dynamite. Alone in Single Player or together in Multiplayer.
Finish Game
Collect all robot pieces
Set off 20 bombs
Collect all cassette tapes!
Catch fish with a trap. Alone in Single Player or together in Multiplayer.
Share a weapon in MP
Eat an entire family
Killed downed enemy with rock
Sleep on yacht
Use the compass
Chop up 50 bodies
Eat an enemy
Make and wear stealth armour
In Single Player, kill 100 cannibals
Revive 10 co-op players
Kill bird with arrow
Share a food or drink item in MP
Kill a bunny. Alone in Single Player or together in Multiplayer.
Cut down 100 trees
Survive 5 nights
Sleep with another player (group sleep)
Revive one co-op player
Survive 1 night