HTML5 AppCache could be used to easily allow offline play.

On my Android phone, it seems to aggressively cache "web apps", so after I added it to my home screen, I've been able to play it when out of Wi-Fi and data reception.

Whoa, this is a great hack. I get so annoyed when my browser cache dumps and tries and fails to reload a page that I had already loaded. Write up this tip as a blog post and submit to HN :-)

It's probably not worthy of a blog post, since it's just a regular feature of Chrome. :-)

  Menu button > Add to Homescreen