My personal favorite is the storyline of cats overtaking all urban landscapes and existing in giant numbers in vine-covered, crumbling skyscrapers. If you want inspiration for what to create, that series gives a TON of amazing images. There's a great series from years back called 'Life After People' that showed the world if people suddenly vanished without warning and it goes from like the first moments until thousands and thousands of years in the future. For example, the kudzu vine in Georgia (USA) needs to be cut back routinely because untended it would overrun everything pretty fast. Just commenting to add a suggestion from a tileset design perspective - love the idea of the 'earth rebooting' concept, but it actually would happen MUCH sooner than a few hundred years.
