Nokia do not control the windowsphone marketplace unlike ovi store for symbian and meego phones. The windowsphone marketplace is controlled by Microsoft. Angry birds is developed by a company called Rovio. You should be contacting Rovio regarding availability and Microsoft if you are having problems with downloading from thr Marketplace
Your phone is a Nokia Lumia 610 Windowsphone. Nokia makes the hardware but the software is by Microsoft Windowsphone. Just like when you buy a laptop, you have Microsoft Windows 8 operating system.
If i have helped at all a click on the white star below would be nice thanks.