I'm pretty sure the core game logic is not on the servers, as widely reported -- I was playing from 9-12PM CST last night, and the servers were supposedly compl

I'm pretty sure the core game logic is not on the servers, as widely reported -- I was playing from 9-12PM CST last night, and the servers were supposedly completely down from 10-12PM -- I was able to continue playing in my city, and wasn't kicked until I attempted to interact with the region. Granted, anything having to do with the region (imports/exports, shared upgrades, etc) was defunct. Additionally, when you exit a city, there's a long pause where your client sends the city state to the server to be persisted (or so the UI tells me) -- another indication that the simulation is not run on the server. My current impression is that the entire city simulation is done on the client, and the server is simply responsible for intra-city interactions and persisting game state.