This can be done, but not as interlocking or real time as everyone thinking. It's designed around "points". Factory (or maybe materials) points, health / hospitality points, etc.
Basically you'll be given some "special" buildings where you can place the other-genre games . Let's say that you have a "60x60 1 level hospital" that when you placed it in the city, you can interact with it via theme hospital style.
Now in theme hospital-like, it has reputation / ratings where it translate directly to "hospitality points" for your city. When you exit the mode, it stopped the simulation and the points freeze. Similar with factory points.
Basically you'll be given some "special" buildings where you can place the other-genre games . Let's say that you have a "60x60 1 level hospital" that when you placed it in the city, you can interact with it via theme hospital style.
Now in theme hospital-like, it has reputation / ratings where it translate directly to "hospitality points" for your city. When you exit the mode, it stopped the simulation and the points freeze. Similar with factory points.