This should play all modern games at medium easily and would be pushing it at high. There are benchmarks for battlefield 4 which is considered one of the most intensive games out, at ultra graphics for an average of 30 frames per second, which is what most people consider playable fps. I personally don't mind lowering settings to get better performance so playing it at high settings would be totally doable. Pretty much you are looking at high for most games this year, medium in two years or so. The gtx 750 ti is a pretty powerful little card, a definite powerhouse for its price.
Pretty much the system can play any game out now and for the next few years.