The MacBook Air does not come with a dedicated graphics card and its processor is underpowered for the task. These issues will follow you over to the Windows side if you Bootcamp. You're also not going to be able to create a very large Windows partition if its HD only has 128 GB total to work with. It's not a machine made for gaming; it's strengths are in other areas -- lightweight thus super-portable, the stable Mac OS, great for web surfing, email, light Office type tasks.
If it were a MacBook Pro with better graphics, it would fare much better in the Sims arena.