While not specifically designed for smartphones, StoryHarp (which I wrote in 1998 in Delphi and then ported to the web in 2018 using TypeScript, Mithril, and Ta

While not specifically designed for smartphones, StoryHarp (which I wrote in 1998 in Delphi and then ported to the web in 2018 using TypeScript, Mithril, and Tachyons) can run in a browser on a phone. StoryHarp makes it easier to write simple rule-based text adventures where players click on available options from a list rather than by typing in text (more like Choose Your Own Adventure books). You can try it out here: https://storyharp.com/v3.0/ https://storyharp.com/v3.0/