crisan_tiberiu is right. DO NOT buy a dual core CPU for gaming. -.- At the very least, wait for the Ryzen 5 CPUs to come out. They will be a better option than ANY old AMD FX series or intel dual core CPU, yes even if you are just gaming. Right now, most games already benefit from 4+ cores, and this trend of higher thread count will only continue. If your budget allows for an i5 quad core, that would also be a much better option over an FX, i3 or Pentium G.
Just don't get a dual core when for a little bit more you can get an i5 or a Ryzen 5 4c/8t CPU.