Here is the full list of all 42 Lies of P achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
[Free from the puppet string] Reach the ending.
Kill the Nameless Puppet.
Find out about the last story of Simon Manus.
Kill the Awakened God Simon Manus.
Find out about the last story of Antonia.
Kill Laxasia the Complete.
Find out about the last story of Venigni.
Strengthen a special weapon to its max level.
Find out about the last story of Eugénie.
Kill the Black Rabbit Brotherhood.
Strengthen a normal weapon to its max level.
Activate P-Organ to Phase 5.
Kill the Corrupted Parade Master.
Modify a Legion Arm to its max level.
Kill the Puppet-Devouring Green Monster.
Kill Champion Victor.
Kill all types of Dimensional Butterflies.
Kill Romeo, King of Puppets.
Harvest Gold Coin Fruit.
Kill the Eldest of the Black Rabbit Brotherhood.
Kill the Fallen Archbishop Andreus.
Kill King’s Flame, Fuoco.
Kill the Scrapped Watchman.
Try to assemble a weapon.
Kill a Stalker.
Tell a lie in front of Hotel Krat Entrance.
Kill the Parade Master.
Destroy an enemy’s weapon with a perfect guard.
Repair a Stargazer.
Deliver a successful Fatal Attack.
[Real boy: They all lived happily ever after] Reach the ending.
[Rise of P] Reach the ending.
Play a perfect tune on the piano at Hotel Krat.
Collect all Legion Arms.
Collect all special weapons.
Collect all normal weapons.
Collect and play all records.
Learn all gestures.
Decipher all cryptic vessels and claim the rewards.
Discover all Trinity Sanctums.
Find out about the last story of Geppetto.
Find out about the last story of Sophia.