This is wrong. The simulation is not serverside. If you disconnect from the servers you can play your city all you want. The only serverside aspect is saves and social (including region play), which would be relatively easier to recreate.
Not necessarily. Implementing client-side saving would be trivial compared to the other kinds of DRM that have been successfully bypassed over the years.
Client side saving is already implemented. In a few instances where I disconnected from the server and continued to play, SimCity would try to push my work to the server on reconnect.
At times this wouldn't work and I would lose my progress, but I'm willing to attribute that to the fact that it was supposed to be a rare case backup mechanism, rather than the necessary crutch it is currently.
Why did they have to disable accelerated time in the single player game? I'm not disputing what you are saying -- the notion that it had a server-side engine for single player games seemed silly -- but that aspect of the story struck me as very odd.
The theory is that the client communicates with the server for saves based upon in-game time not wall-clock time. So cheetah speed forces the client to talk to the server more often for this purpose.
I made my statement based upon my experiences playing. For one, I played the game for 3 hours disconnected from the servers - I knew my progress wouldn't be saved but I just wanted to play. It seemed to work fine aside from region play and that my progress wasn't saved.
Another time I lost my internet connection for 15 minutes. I continued to play. When I got it back, it claimed it re-sync'd my game with the server. As a test I logged out and back in and it all looked the same.
Maybe there is some simulation on the server side. But it doesn't seem necessary based upon my experiences playing the game.
Another theory other than sbov's theory is that there is calculation done on the server side, but only for cities in a region not currently being played. As long as someone is playing in a region, the other cities are basically on rails, so nothing really changes for the players, but they still will correctly interact with cities currently being played.
I am only speculating here but the server may be verifying a client's simulation to prevent IAP/multiplayer cheating. (Who hasn't played the old SimCity games with infinite cash?)
