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