Don't forget rendering engines. Even if you download everything you need, there's a chance the game will look weird (or won't work at all) because the developers only tried one browser.

For all its faults, whether a Flash game worked or not came down to "did you install the plugin?".

Not true. Browsers work with file addresses on your system. You can download an HTML file and all its JS and CSS and if navigate to the path of the HTML on the disk, the website would just behave as if it were served by a static server.

While true for simple things, this is one of those things that’s highly variable depending upon how you built your app. If all your JS is included via script tags and all your image assets are referenced directly, sure, probably.

When anything is dynamically generated things get iffy, though. It’s one of the big problems both Google and services like the Wayback Machine and Pinboard have had with searching and preserving content.

Of course gaming as a whole has also evolved, so it’s less likely you’d ever get a purely single player game in the first place, and who knows if the game will even load in 10 years if it can’t connect to the server to see if you’re registered or not.

> Browsers work with file addresses on your system.

Not for AJAX requests they don't!

If that were the case, 'The Web' wouldn't be pushed like it is right now. 'The Web' is a way to take control from users and put it into the hand of the ones that control the servers. People work on fully fledged binary programs compiled to 'The Web' that your computer just executes while the other half happens on the server. That's as proprietary and inaccessible as it gets.