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.
Collect and play all records.
Collect all special weapons.
[Free from the puppet string] Reach the ending.
Decipher all cryptic vessels and claim the rewards.
Find out about the last story of Eugénie.
Collect all normal weapons.
Find out about the last story of Sophia.
Play a perfect tune on the piano at Hotel Krat.
[Rise of P] Reach the ending.
Kill the Nameless Puppet.
Find out about the last story of Geppetto.
[Real boy: They all lived happily ever after] Reach the ending.
Strengthen a special weapon to its max level.
Find out about the last story of Simon Manus.
Kill the Awakened God Simon Manus.
Learn all gestures.
Find out about the last story of Venigni.
Find out about the last story of Antonia.
Kill Laxasia the Complete.
Discover all Trinity Sanctums.
Kill the Black Rabbit Brotherhood.
Activate P-Organ to Phase 5.
Strengthen a normal weapon to its max level.
Kill the Corrupted Parade Master.
Collect all Legion Arms.
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.
Try to assemble a weapon.
Kill the Fallen Archbishop Andreus.
Kill King’s Flame, Fuoco.
Kill the Scrapped Watchman.
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.