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