Why a snake game belongs in this library
Cairn Snake is the play-first member of the family. Its core loop is continuous target pursuit: the eyes track a moving object, the hand steers toward it, and the game keeps itself inside the limits of preschool motor control. Visual tracking and speeded scanning are real skill families, the same ones behind the processing-speed sections of early assessments. We say this carefully: this game is joy first, practice second. It earns its place by being honest about what it is.
Every pacing number traces to a study
- Boss arrivals pause 3.5 seconds because preschool simple reaction time runs near one second, roughly four times adult speed (Bucsuházy and Semela, 2017).
- Bosses travel below the smooth-pursuit velocity where 4 to 6 year olds lose the target (Ego et al., 2019).
- Touch targets and pickup radii run larger than adult guidelines because children's pointing is more variable than Fitts' law predicts for adults (Yadav et al., 2021; W3C touch-target research).
- Boss fights cap the number of moving things on screen to respect preschool working-memory limits (Roman, Pisoni, and Kronenberger, 2014).
- Progress is a row of pictures that light up, not a fraction. Four-year-olds read pictures.
The full research note ships with the game itself, on the grown-ups page.
The Cairn promises, kept
- No ads, ever. No in-app purchases, subscriptions, or accounts.
- No data collection of any kind. No analytics code exists in the game. Progress lives in local storage on your device.
- No third-party requests. The fonts ship with the game.
- Works offline after one visit. Add it to the home screen and it behaves like an app, over the Atlantic included.
- Hand-drawn flat art, calm pacing, no overstimulation by design.
