How to make your HTML5 game playable offline?

TL;DR: There are only really two techniques you should use to make your game playable offline: Web Storage (local storage) and Appcache. Use local storage to store only information and not to store your games files and assets (especially JavaScript). Use Appcache to cache your games files and assets, explicitly caching all of your files and assets into the manifest file upfront (you’re not going to be able to do much else).