Is this iMac good for gaming?

I'll mention some games to get an idea: BF4, Minecraft, Portal 2, GTAIV or V. At least at low quality.
Thanks by forehand!

It's a "21.5-inch Late 2009" iMac.

-Processor: 3.06 Intel Core 2 Duo
-Memory: 4 GB 1067 MHz DDR3
-Graphics: NVIDIA GeForce 9400 256 MB
-Serial Number W8947MKV5PC
-Software: OS X 10.8.5 (12F45)

It also says: "TM and c 1083-2013 Apple Inc."
So, I don't quite know if it's a 2013 one.

ALSO: if it's not good enough, could I improve it (adding RAM, or something)?

Note: I know it's better to build my own. I'll maybe do that. But I have the opportunity to buy this and I'm curious.

Alan 10.10.2015

Yes. The computer is from 2009 and the operating system will be 2013 which can be updated to the latest version for free…

https://www.apple.com/...whats-new/

Duncan 10.10.2015

Eh-h-h ram…8 megs would be better… But you video card… That's like not going to do well… Gta 4 / gta 5… No way… Bf4 will be scary if impossible… Portal 2 eh-h-h-h yeah you can slide by ( barely )…

For GTA V the barebones minimum is a geforce 9800 gt. And that will only allow low settings ( kinda not really worth playing the game )… But then there are power supply and extra power connection requirements.

Aerialnine 10.10.2015