Don´t buy this game if you are using a laptop, or at least inform yourself before about compatibility. This game have huge problems with intel graphic chipsets and optimus tecnology.
I wasn´t able to run this game myself (I have a dell xps 17 computer)

Try this fix.

http://forums.sega.com/showthread.php?385888-Sonic-Generations-NVIDIA-Optimus-Issue#6

Might get it using NVIDIA, and therefore working properly.

I wouldn't expect this game to run on integrated chips anyways.