I once managed another project that had about 14m visits/mo and made a meager $3000. Bad target demographic.
Should have a donate button on the page (because uBlock..).
Edit: Or: Register to track progress over time with a login, for a low fixed(?) fee.
But I don't know how that would affect my likeliness to see the ad. To improve that, maybe add more natural pause points to the game, so people can have more chances to click?
How did the costs of running the 14m vists/mo compare to http://zty.pe? Different times, and probably different kind of site, but did the experience change the types of applications you tried to build?
The project with the 14m visits/mo generated 700tb of traffic and required half a dozen servers. Cost was around $2000/mo with traffic being the most expensive part. (I complained about traffic costs with cloud hosters a while back: https://news.ycombinator.com/item?id=11301085)
I tried to bookmark it by hitting command-D (in Safari on a Mac), but since you capture all keystrokes, I couldn't bookmark it. Perhaps you'd see a bump in your numbers if you allowed command-D through?
Windows, Chrome, bookmarking seems to work fine?
P.S: This game is seriously fun!