The easiest way to fix the deltarune/gayshit spam would be for the admin to limit pixel creation to within 10 miles of your current location. Then you'd actually get local culture/humor represented on the artwork, and if people wanted to put weird shit, their town would automatically be outed as retarded. Plus, trolling would be more respectable because it would mean you actually traveled to the location to grief it. The ideal version of this would be an AR app where you have to walk exactly where you are drawing and you can see the pixels in the sky. Then you'd have people defending locations like pokemon go gyms.
Regardless, this has to be reset yearly to free up canvas (and to bring in new users around the new year after inevitable lulls). Then you get maps from each year you can look back on.