SimCity is finally being updated to receive an offline mode, but the task of changing the server-based title to work locally wasn't as simple as you might think, Simon Fox, lead engineer on the Single Player Mode has revealed.

This is what the Fox said:

"The original creative vision for SimCity was to make a game where every action had an effect on other cities in your region. As such, we engineered the game to meet this vision, setting up the player's PC (client) to communicate all of its information to the servers. That means that our entire architecture was written to support this, from the way that the simulation works to the way that you communicate across a region of cities. So yes, while someone was able to remove the "time check" shortly after launch, they were unable to perform key actions like communicating with other cities that they had created locally, or with the rest of their region(s), or even saving the current state of their cities.

"My team did, however, see a path forward towards Offline, one that would maintain the integrity of the simulation. Lucy once said that Offline wouldn't be possible "without a significant amount of engineering work", and she's right. By the time we're finished we will have spent over 6 ½ months working to write and rewrite core parts of the game to get this to work. Even things that seem trivial, like the way that cities are saved and loaded, had to be completely reworked in order to make this feature function correctly."

Fox added that because the local system was now being tasked with carrying out simulation calculations, optimisations had to be made.

"All of the regional simulation needs to be done locally. The algorithms governing trading between cities needed to be retuned in order to make the behaviour between cities more responsive for this type of play. This in itself required major optimizations in order to run the simulation locally. We have an obligation to make the game fun and functional on all specs of machines. We wouldn't want someone who was enjoying the Multiplayer game to find the Single Player game crippled due to poor optimization.

"And it's not just adding, we had to remove parts of the game for it to function properly as well. This means removing lots of code integral to Multiplayer include code and UI supporting Trading, Social Features, Global Market, Leaderboards and Achievements. And, all without crippling the Multiplayer game."

The offline mode has recently hit alpha and is now in the final stages of testing before being released as part of Update 10.