Playing franchise, I have a few zoos for each biome. When I finished building in every biome, I have increased my builiding skills so much that didn't like the first zoo I've built anymore. So I deleted it and built it again with my new skills. When finished, I deleted and rebuilt the second biome zoo. When I have rebuilt the very last zoo, my building skills increased again and I don't like the first zoo anymore, so I will delete it and build it again... and this is how it goes on forever since that day. [imagine Elton John singing the Circle of life]