One mind (belonging to an Agent Nein) is a painfully orderly cube which is plagued by little men who censor anything unusual. Find Nein's safes and the story of his mother's death is revealed.
Agent Vodello's safes conceal her trauma as the only survivor of a school fire. It only becomes more involving as you explore the childhood torment of a Hollywood actress, or the mind of a schizophrenic. It's not quite Spyro the Dragon.
Progress means extra psychic abilities that are used as devices to trigger entertaining comedy sequences. It's the replacement of, "Use fake barf on clock" with, "Use pyrokinesis on Milkman."
But the game has a major flaw: the edge detection is broken. Raz regularly falls huge distances when he should have gripped the ledge. It's incredibly frustrating because it means endless repetition of the tricky platform bits, and violent swearing.
It would take forever to write down everything I love about Psychonauts - every microscopic detail, every hidden guffaw-inducing gag, every moment of genuine emotion. Instead I have only this small moment to say: I implore you to play this game.