The Hitchhiker's Guide to the Cataclysm is a guide to the zombie survival roguelike game Cataclysm: Dark Days Ahead. You can search for things in the game, like items, or monsters, and find useful information about them. The data in the Guide comes directly from the JSON files in the game itself.
The Guide stores all its data locally and is offline-capable, so you can take it with you whereever you go. There's nothing to do to make the Guide work offline, just visit the page and it will work even without internet access, as long as you've visited it once before. It's also installable, so you can pop it out of your browser and use it like a regular app.
More popular than the Celestial Home Care Omnibus, better selling than Fifty-three More Things to do in Zero Gravity, and more controversial than Oolon Colluphid's trilogy of philosophical blockbusters Where God Went Wrong, Some More of God's Greatest Mistakes and Who is this God Person Anyway?