Is it Web App or Native App? In another words, can I play the App even without internet connection?
hello dannybao, web apps are native apps to firefox os :-)
there are packaged apps written with html5-dechnology which will always work offline - but also for apps hosted on the web developers have the tools to support offline operation. some details about that (though primarily focused on developers) are available at https://hacks.mozilla.org/2013/02/getting-started-with-open-web-apps-why-and-how/, https://marketplace.firefox.com/developers/docs/apps_offline & https://developer.mozilla.org/de/docs/HTML/Using_the_application_cache