It's absolutely awful for most high end games. It can handle games with lower end graphics to a moderate level. It also provides no upgradibility so even if you wish to tune it up it would be impossible to do so. I think you would be better off looking at a normal desktop and buying a graphics card. It is relatively simple and you don't have to necessarily spend too much.
Absolutely not, in terms of tame games you would play in a browser this would be fine, however any proper games that I expect your son would want could not even run on this computer. You can get a decent computer that will run games for a low price