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