Just purchased this myself, decent price if you can overlook the mediocre reviews and "some" bugs :P
About the game (copied from steam page):
Cities XL 2012 is the new version of the famous City Builder, which allows you to build, develop and connect together cities of all sizes and types on Cities XL planet. To build your cities, the version 2012 now offers a huge choice of nearly 1.000 buildings and structures and over 60 different constructible, huge, varied and incredibly detailed maps.
Review: http://www.youtube.com/watch?v=jYMCIyfwD6Y
System Requirements
OS: Microsoft Windows XP SP3, Vista SP1 or 7
Processor: Intel/AMD 2,5 GHz or higher
Memory: 1 GB RAM (XP), 2 GB RAM (Vista/7),
Graphics: ATI Radeon HD 3850/INTEL HD/NVIDIA Geforce 8800 or higher, 512 MB RAM
DirectX®: 9.0c
Hard Drive: 9 GB disk space
very fun game and a great re-invention of the genre after simcity, but I was ultimately pushed away from it due to bugs and crashes