I don’t consider myself a hardcore gamer (I rarely play online, for start), but I do like to occasionally play 4x games (Civ 5 and many space 4x games like Endless Space or Sins of a Solar Empire), flight simulators and generally simulators of something (SimCity etc.)
I have this wonderful rig in my studio with three large monitors and a pretty beefy GPU and I’ve got to use it for something other than just music software… 
I’ve never written game music and generally I find it the most cliched of any type of soundtrack. With the usual rare exceptions, of course.