Here’s a typically convoluted but excellent deal on Steam:
If you want the latest Cities XL 2012 game which is due for release in about a weeks time it will cost you £29.99 unless you have the last version cities XL 2011, in which case you can get it for 61% off (or more in the US) that’s only £11.69. If you don’t have Cities XL 2011 you can buy it for £19.99, which would make the total for both two games if you purchased the 2011 edition first only a few pounds more than the latest version, i.e. £31.68. Now, if you have the original version of Cities XL or the Limited Edition, which were released back in late 2009 you can get 50% off Cities XL 2011, the original Cities XL Standard edition only costs £9.99, so if you purchased that first you’d be able to purchase Cities XL 2011 for only £9.99 also, making a total of £19.98. That would also entitle you to 61% (or I think 67% in the US) off the latest version, which would mean you would only be paying £31.67, that’s a penny cheaper than only purchasing the 2011 and 2012 versions, so you are effectively getting the original for free plus a penny discount. There’s also a limited edition that costs £3 more to purchase.
There’s enough new stuff and some improvements in the graphics to make it worth purchasing the 2011 version once you've got the original; especially as you'd effectively be getting the first one for free. As yet I’m not sure how much extra you get with the latest version. Looking at the screen shots over on Steam (You can see them HERE) the game does look better, but that may just be the way the developers have used the screenshots to show the best of the game. The following is what Steam says about the latest version
The Game:
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.
With Cities XL 2012, become a virtual mayor. Answer the growing needs of cities that you create, such as energy supply and transport. Find the perfect balance between the various services you provide to your citizens, such as housing, recreation, or jobs. Finally, sustain the proper economic development of each city that you administer, by setting up trade between them: you can specialize certain cities in specific areas to fill in the needs of the others... this will ensure an economic balance on a gigantic scale, which will allow you to develop more!
You can check out the original and the Limited Editions HERE and HERE, the 2011 edition HERE, and the 2012 Edition HERE.