SimCity now supports mods providing all guidelines established by Maxis are met
SimCity now supports mods, providing all mods created adhere to guidelines set forth by Maxis. If you are particularly into modding, you can look over the blog post from Maxis here, as well as look over the guidelines. The gist is this: don't mess with the multiplayer or foul up the integrity of the gameplay; keep it ESRB E10+ and PEGI 7; don't use copyrighted material; and remember that the SimCity EULA and EA’s ToS "supersede these rules," according to PC Gamer. Meanwhile, in post a on the SimCity forums, the firm reiterated it's still looking into offline mode for the game.