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