A:
If you are looking to game than here is my suggestion. Go get a AMD Radeon R270 and a PSU (Power Supply Unit) with a wattage of around 500-600. I'm about to do this myself I just haven't gotten around to it. I know a lot about computers as I do coding for software an programs an I am also capable of building computers from the ground up.
Only thing is the AMD Radeon R9 270 may or may not fit within your Chassis (Computer Case) as I haven't purchased it yet to find out for sure. Judging by the size dimensions it seems that it will most likely work.
Another thing is if you are installing a GPU (Graphics Processing Unit) on this machine you will need to make sure you have a solution to heat dissipation. The form factor (size relative to motherboard) of this case is a Micro-ATX (1 up from the smallest available) so there is going to be very little room within the case once you add a GPU & PSU inside. Therefore I suggest finding a good fan of the right size to install on the backplate (the vent below the PSU vent) to help with any heat problems. When a computer gets too hot inside it can ruin your CPU. Luckily there are programs installed on this computer (from asus) that allow you to check the internal heat an everything.
Anything else you would like to know?