Interesting that you have the same feeling.

I used to like RTS-style/city builder games and put endless hours in them (think simcity, rollercoaster tycoon, settlers, ... ).

I barely play games anymore, but now I focus more on short (sidescroller) action games. Where each level lasts only a few minutes. (super meat boy, zombie night terror, hotline miami, ...)

Maybe it's a case of instant gratification seeking. But it seems to work for me.