There is like no way anyone is going to crack this because the security is just to hard, but if you downloaded this already you can make a 7 day trial account for it and play online for the time. 1. Go to citiesxl.com and click on the sign up button in the menu. it should bring you to a registration screen.
Ignore the cd key button and just fill in all the information for your online account and click the send registration button.
On the next screen it will ask for a cd key but just scroll down and there is something that says activate 7 day trial.
There, now you have a user name to log in with for the next 7 days and you have access to all the multiplayer stuff. Until someone gets a better idea il be playing for the next 7 days