Here is the full list of all 37 Psychonauts achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Spy on Bobby's love life.
Hear Vernon's Ghost Story.
Witness Maloof's transformation.
Cook and consume two different kinds of roast in one sitting.
Complete Sasha’s Shooting Gallery.
See yourself through the eyes of many others.
Complete Meat Circus.
Achieve Rank 101.
Sort all Emotional Baggage.
Gather all Figments.
Crack all Vaults.
Complete The Asylum.
Introduce all Camp Kids to Mr. Pokeylope.
Re-brain the Children.
Redeem all 16 Scavenger Hunt Items.
Achieve Rank 80.
Buy an item from the Camp Store on Christmas.
Give the Coach's speech on the stump.
Complete the Punchy Target mini-game.
Revisit all brains after completion.
Uncover Milla's Secret.
Find all Golden Helmets.
Read many bulletin board messages.
Discover the secret history of Whispering Rock.
Find Edgar's Secret Garden.
Complete Gloria’s Theater.
Achieve Rank 60.
Complete Waterloo World.
Complete Black Velvetopia.
Earn all Merit Badges.
Complete The Milkman Conspiracy.
Use the bacon. A lot.
Complete Lungfishopolis.
Achieve Rank 40.
Complete Milla’s Dance Party.
Achieve Rank 20.
Complete Basic Braining.