Fighting games.

As you probably now, I mainly play fighting games. Yes, I do play other things (particularly JRPGs. certain indie games, whatever genre Dark Souls is, and character action games), but the only games that constantly stay in my console are fighting games. I pretty much play anything that isn't Tekken (too complicated) or Mortal Kombat (Focus on gore over actually deep mechanics). Personally, my favorite fight game is King of Fighters 13. I should also note that I am not that good at them though...

In fact, my motivation for buying an Xbone over a PS4 was due to A: the better netcode of Xbox Live, and B: KILLER INSTINCT!!!

I think the fact that I mainly am only concerned about gameplay comes from my fascination with fighting games. Most fighting game plots are literally the same thing, if they even have one. Smash Bros doesn't even have a plot (Subspace Emissary doesn't count. Vanilla Brawl is terrible, play Project M instead) Fighting games are ALL about gameplay and execution.

Look at that fantastic combo... What other genre can produce that level of insanity?