It's not good practice to rely on a user's cache. If they visit your site twice in a span of a day, they may have already cleared their cache or pushed your files out with other sites' files.
This article demonstrates a pretty good method to reduce unnecessary byte transfer which will ultimately speed up page loading.
Caching is still a good idea, because if a user decides to browse to another page on the same site in the same visit (or refresh/post a comment), a significant fraction of the data required for it has already been loaded. If a user does come back, there's always a chance that your stuff will still be in the cache.
By far the most interesting thing is the overlay of map with tweets. I'm using a cinema display, so can't say I have problems reading small type. Although the color scheme looks very Blade Runner, it makes overlaying only a few options difficult to grok. Scrolling is slow.
Still impressed this was rolled out for a video game. Have there been any other presentations like this in the past?
This article demonstrates a pretty good method to reduce unnecessary byte transfer which will ultimately speed up page loading.