Just to be clear, we can actually use images like other "million-dollar pages" or we're limited to colored pixels only?
Currently you are limited to pixels, but you can define a set of those in "AUTO" mode, and interface will place them on canvas the moment you mine the pixels. Ability to save/load those (as JSON documents, and later as PNGs) is coming, but it is not there yet.
You might want to consider the following things: Increase your placement rule to a few hrs [at least].
In that case someone who keeps mining will get an enormous head-start, and user that recently joined most likely won't have the patience to wait till he mines enough to make any kind of a difference. He can place his pixels in the places that are not used, of course, but in that case someone who accumulated a lot of pixels will have an opportunity to completely obliterate the newcomer, and, again, he is very unlikely to have the patience to wait till the balance is tilted in his favour.
I do want to encourage people to keep mining, of course, but for now i think that 10 minute rule gives them a lot of head-start already: even my pathetic little i5-3210M is able to accumulate 10 PX on average.
Change the other rule to somehow guarantee each pixel to be overwritten only after a certain amount of time has passed.
TL;DR: I want to drive people to the billboard by giving them an opportunity to throw tomatoes at ads they dont like. Implementing this suggestion will interfere with that, unfortunately.
The only way this project will work, in my opinion, is if users are able to compete and collaborate with each other the same way they did on /r/place or plxs.space: otherwise, there will be no incentive to come back to the page, and, therefore, no views => no clicks => no mining. Ability to overwrite someone else's pixel, even if for a fraction of a second, is essential: it gives player a sense of progress and allows him to experience a sense of gratification.
With all of that being said, it becomes increasingly obvious that for some weird reason i personally cannot fathom, people don't want to spend their time and effort to set up mining on their machines so that they can place pixels on canvas nobody is currently watching/playing on. Who knew, right?
So i think i will push template save/load a little bit further into the future and start making giveaways instead: by following specifically crafted link users will be able to get themselves, say, 99 pixels for free upon registration. Might also add some referral-program-like features to that. Will update the first post and write to the telegram channel when i am done with it.