There are many games that are "playable". However, that depends on what is "playable" for you. For some hardcore gamers it the desktop / laptop cannot play games on ultra graphic settings with at 50 FPS, then they consider the game to be "unplayable".
You will not be able to upgrade your graphics card. The Radeon HD 7670m is a graphics chip for laptops which is soldered into the motherboard. It is an okay graphics chip. It is basically around the same performance (or a little better) than the nVidia GT 540m, GT 630m, GT 720m. It is almost as powerful as the integrated Radeon HD 8650g graphics core in AMD's Richland generation A10-5750m APU.
It is good enough to play many (but not all games) at either low or medium graphic...