Have you ever watched a short animation from Disney?

https://www.youtube.com/watch?v=ScI8OOqsqrQ

According to this video, I thought of an animal hotel idea!

You manage a hotel where animals come to rest, you have to assign the animals to a room manually but after a bit, they will leave and pay you, use that income to upgrade the rooms or build more rooms. You might need to go deeper and deeper to build, posing new challenges.