Which mac should I get

I plan on doing a lot of gaming. Sims 3, Gta 4, Fifa etc.. Which should I get, the macbook pro 2012 or the iMac 2011, the 2012 Imac and retina macbooks are out of my budget, I'm really considering the macbook because or portability and due to the fact that there are a lot of power shortages in my town, I'm just worried that after all the intense gaming, the commputer would'nt last long. So should I go ahead and buy the macbook pro or should I buy the imac?