I explained on the page description that how I tried to add the theme didn't work out, so scrapped that part, but still wanted to finish the game.
The difficulty does ramp up after a bit, that was intentional. I don't expect everyone to reach the end. As for diversifiers, also explained on the page, didn't use any (they where not required, just like the theme is semi-optional) but I did use my own diversifiers in the art. 13x13 pixels and only 4 color EGA palette.