Psychonauts

Tie each world to one person so its theme has a purpose. Collect-a-thon platformers like Banjo Kazooie had fairly random world themes. Psychonauts sets every level inside someone's head, so the look of each world and what you do there reveal that character's personality and hidden pain.

Coach Oleander's mind is a battlefield, Milla's is a party and Sasha Nein's is an orderly monochrome cube. Mark Brown's verdict: "what the level looks like - and what you end up doing in that level - says so much about the character in question."

A design idea cut from one game can anchor the next. Tim Schafer wanted a peyote vision quest inside Ben's mind in Full Throttle, but LucasArts cut it. The idea returned a decade later as Psychonauts, the first game from Double Fine, the studio he formed with a few friends from LucasArts.

Released in 2005, it sold poorly but became a cult classic. It keeps some item puzzles from Schafer's point and click adventures like Grim Fandango and Day of the Tentacle.

Tutorial levels can teach moves and introduce characters at once. The first three minds, Oleander's, Milla's and Sasha's, teach jumping, shooting and levitating while hiding repressed memories under a tidy surface.

Milla keeps her nightmares in a locked room, and Sasha's packed cube explodes into scenes from his past. The game gets really good once Raz crosses the lake to the asylum, where the minds are unmoored from reality.

Showing character through play beats a cutscene or dialogue tree. Players have to work out what each element represents and link it to clues they find, so they understand the troubled cast by playing rather than being told.

Mark Brown argues this, more than its platforming or puzzles, is why the game earns its cult status. BioShock's Sander Cohen level uses the same approach less successfully.

Make the player perform the character's delusion. Boyd fears being watched, so his level has you find disguises to infiltrate groups of agents and use clairvoyance to see how others see you.

Agents in trench coats pose as housewives, plumbers and grieving widows. "The actual gameplay of the level has you obsessing over how other characters see you."

Warped geometry signals a twisted mind before any dialogue. Boyd's mind is a cozy suburb bent, skewed, tied in knots and folded over itself, filled with surveillance cameras and prying eyes.

Removing an expected system shows how far a world has diverged. Other stages have censors that block unhealthy thoughts; Boyd's has none. Milla's nightmares stay locked away, while Boyd's roam free and become a boss fight.

The absence works because players have learned to expect the censors. Boyd is a gibbering mess in the real world, yet his level shows how he truly feels.

Let a hazard stand in for a character's emotion. In Edgar Teglee's Black Velvetopia, a bull embodying his rage charges down narrow streets and knocks Raz back to an earlier point if it hits him.

The setback mirrors Edgar's unending battle with that part of his psyche, so the player feels his frustration through the challenge.

Draw puzzle tools from the character's identity. Inside the artist Edgar's mind, Raz uses paintings as doorways and magic props, so solving puzzles deepens understanding of him.

A mood switch turned Gloria's bipolar disorder into a mechanic. In Gloria's Theater, Raz hits a switch that flips the play between happy and sad, which can make enemies appear. The final climb to the rafters needs both moods to beat her inner critic.

The level stages her troubled upbringing as a play, including the line "She doesn't have time for an ugly little girl like you."

Hide backstory in collectibles that make the whole level readable. Each mental vault reveals more about the character. Edgar's shows his girlfriend taken by a football player and him losing his next wrestling match, explaining the four wrestlers Raz fights and the high school buried in the sewers.

Oleander's vault reveals he never made it into the army. The levels have loads of collectibles, probably too many, but the vaults are the key; Brown calls it archeology, psychotherapy and English lit while punching a giant fish.

Treat sensitive subjects with empathy, avoiding stereotypes and easy cures. Psychonauts sometimes reduces mental illness to stereotypes and easy cures, but despite being genuinely funny it rarely makes the asylum patients the punchline.

Each asylum level ends with fixing the character's disorder so Raz can bypass it, a game goal rather than a medical one.

Combining two verbs in a timing window creates a new move. Attacking right after a jump unleashes Psychonauts' devastating palm bomb.

It takes timing and an understanding of how verbs link, building toward a move set players learn and memorise.