A publication about two constraints

Almost everything written about mobile games is written about their business. This publication is about their design: the decisions made because a screen is held in one hand and a session lasts about as long as a queue.

Those two facts are not soft. A fingertip is roughly a centimetre across and arrives without a cursor, which is why Apple's Human Interface Guidelines specify 44 points and Material Design specifies 48 density-independent pixels. A thumb pivots at the heel of the hand, so reach is a curve rather than a grid. A commute ends when the train arrives, not when the player is finished. Every piece here takes one constraint of the hand or the session and looks at the design that answers it.

What is in scope

Games that have shipped and are documented: FarmVille, Hay Day, Clash of Clans, Candy Crush Saga, Cow Clicker. Studios described through their published design practice — Zynga, Supercell, King. Researchers and designers named for work in the public record: Steven Hoober's field observations of how phones are actually held, Jesper Juul's account of casual play, Ian Bogost's satire and the writing around it.

What is out of scope

No gambling, wagering, odds or real-money mechanics of any kind. No reviews, scores, rankings or "best of" lists. No store links, prices or purchase advice. No download figures, revenue numbers or user counts, because we cannot source them. No claims about any company's finances, internal conditions or plans.

The site carries no dates. A design constraint that came from the shape of a hand does not expire, and a piece here is either current or wrong.

How it is organised

Seven sections, twenty-two pieces. Navigation sits at the bottom of the screen rather than the top, inside the reach of one thumb — which is the same argument the publication makes about everything else. The full register is one page.