The 2D game can't be played locally as a HTML file without launching a local webserver. https://forum.unity.com/threads/how-to-manually-start-a-localhost-version-of-web...
There's an APK in the attachments isn't there? No need for joiplay.
If by existing story you mean the text game, there are already graphics there including scenes and so on but it got too difficult to maintain as a single developer because it's written in JavaScript and a ton of testing is involved to fix some annoying bugs. However, there'll be an update to the text game sooner or later.