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