Homeostat
Hold a regulated variable inside its band by working the body's effectors against a disturbance — negative feedback, with gain and lag, by hand.
4
levels3–15 min
a run, player-paced30
actions of integrityReal time
no countdown; step mode plays it turn by turn
Homeostat
Hold a regulated variable inside its band by working the body's effectors against a disturbance — negative feedback, with gain and lag, by hand.
A regulated variable — core temperature, blood glucose, a leaf's water content — drifts while the world outside misbehaves. You work the effectors the real system has: shivering and sweating, insulin and glucagon, stomata. Effectors lag behind their orders, so a correction ordered late lands late and overshoots. Time an excursion outside the band erodes integrity; the clock itself never does. The world runs fast, as a teaching model, and step mode runs it one tick per key press.
Levels
4 levelsThe tag on each level says how it gets harder. Levels gate on ideas, not on each other — jump wherever it gets interesting.
What decides the outcome
The game never restates the science — it imports it. These are the model layers that do the deciding.
The negative-feedback controller (`feedback-control`): an effector's first-order lag toward its order (`laggedEffector`), the regulated variable's response to effector and disturbance (`regulatedVariableStep`), and the negative-feedback law the finale's controller runs (`negativeFeedbackCommand`); and the seeded generator type. The game states no law of control of its own.
Why it teaches
The author's own delete-the-science argument: remove this game's substrate and there is nothing left to choose.
Every order is a feedback decision: which effector, how hard, and — because effectors lag — how early. Without the substrate's lag and integration the variable answers every order instantly and the game is a reflex test; with it, the learner discovers by hand that a full correction at the first sign of drift beats a panicked one at the band's edge, that an antagonistic pair fights itself when both are on, and in the finale that too much gain with a delay rings rather than holds.
Accessibility
The contract's declarations, stated before you commit to a run.
Keyboard
Playable start to finish from the keyboard.
Screen reader
Partial screen-reader support; see the game's notes.
Motion
Reduced-motion variants provided.
Audio
Silent — no sound, and nothing on screen moves on its own.