From IFWiki

Yarn is an interactive fiction platform that includes an authoring system, a publishing platform, and a set of mobile apps (iOS & Android) where readers can download published stories and games. It was originally developed by Ryan Epp.

Yarn games run natively and are all cross-platform by default. They are choice-based and feature support for variables, forks, images, sound, animation, css-like styling, and timed delays.