Visual Novel for All Devices. O₂ Engine is HTML5-based visual novel engine. It works on Windows, Mac, iPhone, iPad and Android. Compatible with KAG3 O₂ Engine interprets KAG script. It is compatible with Kirikiri, one of the most popular engine to develop visual novels. Pure HTML5 Fully written in HTML5, therefore runs on modern browsers, including mobile. No Flash, no applet. App Packaging Develo