http://www.ign.com/articles/2014/08/27/bigger-simcity-maps-created-by-modders?abthid=53fe1b3c97c5fc0f47000010

Update: This story originally stated that Maxis had claimed larger cities "weren't possible due to technical restraints." The actual statement was that increasing city size was possible, but would have too great an impact on performance for players on lower-end PCs. We have made the correction and regret the error.

A new SimCity mod to increase the maximum size of your cities has been released.

The Project Orion mod increases the possible boundary size of your cities by 3km, which works out at around four times the default size. The mod is still in beta, and a range of issues exist, including lag once you stray beyond the original boundaries of your city and issues placing other cities nearby.

Following launch, SimCity developer Maxis took a lot of heat for failing to provide an offline mode for its city-building sim, along with bigger city sizes to play with. Though the former was fixed earlier this year, Maxis claimed larger cities simply weren't practical due to performance restraints.

"We’ve put months of investigation into making larger city sizes, reworking the terrain maps, changing the routing algorithms of our agent-based system and altering the way that GlassBox processes the data in a larger space," general manager Patrick Buechner explained.

"After months of testing, I confirm that we will not be providing bigger city sizes. The system performance challenges we encountered would mean that the vast majority of our players wouldn’t be able to load, much less play with bigger cities. We’ve tried a number of different approaches to bring performance into an acceptable range, but we just couldn’t achieve it within the confines of the engine. We’ve chosen to cease work on bigger city sizes and put that effort into continuing to evolve the core game and explore an offline mode. Some of the experiments we conducted to improve performance on bigger cities will be rolled into future updates to improve overall game performance."