Mozilla’s Firefox OS is based on Gecko — the same core rendering engine that its desktop and mobile Firefox web browsers use. This unified framework goes to the essence of what Firefox and Mozilla are about. Mozilla sees the future of apps and browsing as two sides of the same coin. To push its vision for “Open Web Apps,” Mozilla has rolled out v29 of Firefox for Android, which enables you to download and install Firefox OS marketplace apps on your Android device with no additional configuration.
With the new support for Android, all you need to do is install the updated Firefox browser from Google Play — attempting to grab anything from the FF marketplace with Chrome results in an error. The apps will go through the standard Android installation dialog (packaged as an APK), and even show up in the app drawer. They open like normal apps, but all the rendering is done through Firefox’s Gecko engine. As for usability and performance, web-based apps like this have definitely come a long way over the years. They work, but the design language is much less refined.
So, go ahead, have some fun!