First of all thanks for playing. 🙂
The initial/bigger idea was to tell a small story. Something like, a kid bought a cute little mouse and had the idea to show the mouse for a little admission fee and then starts to buy more and more cuts animals, that brings more people to watch them, until upgrade 5 or so, where the parents step in and tell the kid that it gets out of hands and it's time to get the animals a new home. Which could also could have worked as kind of reset mechanism to multiply the income for the next run.
Obiously it was way too big for the time I had available.