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.
Play a perfect tune on the piano at Hotel Krat.
Find out about the last story of Sophia.
[Rise of P] Reach the ending.
Kill the Nameless Puppet.
Strengthen a special weapon to its max level.
Find out about the last story of Simon Manus.
Kill the Awakened God Simon Manus.
Collect all normal weapons.
Learn all gestures.
Find out about the last story of Antonia.
Kill Laxasia the Complete.
Find out about the last story of Venigni.
Discover all Trinity Sanctums.
Kill the Black Rabbit Brotherhood.
Strengthen a normal weapon to its max level.
Kill the Corrupted Parade Master.
Collect all Legion Arms.
Activate P-Organ to Phase 5.
Kill the Puppet-Devouring Green Monster.
Kill Champion Victor.
Modify a Legion Arm to its max level.
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.
Try to assemble a weapon.
Kill the Scrapped Watchman.
Kill a Stalker.
Destroy an enemy’s weapon with a perfect guard.
Tell a lie in front of Hotel Krat Entrance.
Kill the Parade Master.
Repair a Stargazer.
Deliver a successful Fatal Attack.
[Real boy: They all lived happily ever after] Reach the ending.
[Free from the puppet string] Reach the ending.
Collect all special weapons.
Collect and play all records.
Decipher all cryptic vessels and claim the rewards.
Find out about the last story of Geppetto.
Find out about the last story of Eugénie.